It's the same train, with 2 TGV train sets. SNCF insists on giving both train sets a different train number and doing separate yield management for both train sets, so it can happen that one is €10 and the other €20. They both have a bar, according to the SNCF website.

This is a different way of handling two trains running together, but there seems to be a bug. No reason to worry, though: According to sncf-connect, they are both TGV inOui, both have a bar and both serve all those stops in between. Must be an error in the data the b-europe site gets for these trains. So book either of them.

@Schelte @rvdborgt Thanks so much for the explanation, you guys are legends.

Now I can go ahead and make the bookings :)

I just booked the seat reservations for this TGV 6077, and selected seat face to face as a reference, however, the assigned seats on our tickets are next to each other with an aisle in between 

I was trying to ring the contact number to see if I could swap to seat 71 and 74 instead of the assigned 71 and 72 but couldn’t get through 

Considering it’s a relatively long train ride, I am really not happy about the seats we were given. 

Would there be other ways to contact Thalys regarding possible seat changing?

(I successfully changed seats with reference number on Eurostar website after booking through SCNB for EUR9116.)

This is not Thalys, it's an SNCF train.

Belgian railways were probably closed already, considering their opening times:

https://www.b-europe.com/EN/Contact/Contact-Centre

I'd try the number mentioned in the last line, since that will be a lot cheaper to call.

Thank you @rvdborgt :) I got it wrong and checked the wrong seat plan, I think 71 and 72 might actually be a club duo. 

Now I have trouble of booking seat reservation for Nice to Geneva, I want all the travel to be on the same day. Is the best way to book Nice-Lyon, and Lyon to Geneva separately?

I could book Nice to Lyon on travel.b-europe.com.

For the Lyon to Geneva train, I couldn’t find an available reservation on any train operators’ websites, on Eurail planner website, it shows as below. (Same goes to Geneva to Zermatt too) 

Does that mean there's no options/need for seat reservations? Can we just hop on and sit anywhere we want?

The Lyon-Geneva train you're showing is a regional train. Reservation is not possible, just hop on. For Geneva-Zermatt, reservation might be possible between Geneva and Visp but that would be a waste of money. Just hop on. In Switzerland, reservations are available for some trains, but they're not needed and are IMO a waste of money. Only for a few special panoramic express trains, reservations are really needed (and for some of them only if you want to use the panoramic coaches).

Thanks so much for the advice @rvdborgt :) I won't bother booking these reservations then. Hopefully there will be seats available for the trains we planned to get on as we need to get to Geneva at 14:35 so we will still have kind of half day to explore before we head to Zermatt the next morning.

I have already booked the Bernina Express (the panoramic coaches), and will book the Glacier Express once the reservations open for the date. 

They are indeed. For 1st class you can check the seat map by simulating a booking on sncf-connect.com. When buying regular tickets you can (only when travelling 1st class) select your seat from a seat map.

That I know, only Eurostar allows changing seat selection after purchase. With SNCF I've tried on the phone and they can't change the seat selection (unless they would re-book the tickets).

Thank you @rvdborgt :) I got it wrong and checked the wrong seat plan, I think 71 and 72 might actually be a club duo. 

They are indeed. For 1st class you can check the seat map by simulating a booking on sncf-connect.com. When buying regular tickets you can (only when travelling 1st class) select your seat from a seat map.

That I know, only Eurostar allows changing seat selection after purchase. With SNCF I've tried on the phone and they can't change the seat selection (unless they would re-book the tickets).

Thank you @rvdborgt :) May I please ask which website did you use for the TGV train seat plans (as shown in the above picture?) 

@bleusquirrelThis one https://www.sncf-connect.com/, like @Schelte said before. You have to simulate booking an ordinary ticket. (And choosing seats it only works for 1st class I think).

There are other websites too, like the site of seat61, but you already need to know the type of train you’ll be travelling on. Which is relatively expert knowledge ;)

VagonWeb is also a good option. But anyhow in quite some booking processes you can’t select your seat. Usually this doesn’t really matter too. First class has usually good window views, whatever the option.

The only extra trip I would give you, is to be attentive for window seats, that are not window seats. Especially in Germany’s newest high speed trains this is a nuisance. It’s not nice to look at some white plastic for hours, instead of a window.

Thanks for all the tips @BrendanDB :)

I really want to be able to choose seats for the trains which allows seat preferences or even seat selections. I figured out to check the type of train on Raileurope.com when testing with booking normal tickets. I listened to your advice from the other day to select “seats facing each other” for preferences and it worked I was lucky enough to have had assigned club duo for three train rides so far :)

While you are here, can I please ask you another question which is irrelevant to this topic? (I am so sorry that I always have so many questions )

So I was booking Vienna to Ceske Budejovice on Oebb.at for 13 June.

I wasn't sure if I was supposed to book both reservation and one-way journey tickets as what's shown on the picture below, and luckily I the first leg has 1st class and allow seat selections.

Did I do it correctly? (It’s kind of like the Venice - Munich train which I was guided to do so.)

Just the seat reservation will do for that journey. Sometimes it’s simple

No need for extra tickets (even if they cost nothing).

I am so confused :(

In what scenario do I need to buy extra tickets not just the reservation?

In my other post of the Venice to Munich train, I was suggested by @MartinM that I need to buy both tickets and reservation for that train. 

I don't know how to tell…. It’s so complicated 

That’s just a „specialty“ for the Italy-Austria-Germany trains operated by ÖBB (and that is a supplement not a real Ticket). For other trains not. 

Thanks @MartinM :)

What about the other Italian domestic trains, do I need to book both tickets and reservations if I book on Oebb.at?

Nope, only the reservation :) 

Thank you 

For italian domestic trains you need a reservation for IC (3 EUR) and Frecciarossa (10 EUR) trains. 

Eurocity to Switzerland and Germany via Switzerland have compulsory reservations in Italy (10 EUR) or for international rides (11-15 EUR). 

Eurocity to Austria, Slovenia and Germany via Austria have optional reservations, but you need to pay a fee to use them in italy (10 EUR 2nd, 15 EUR 1st). Reservations if you want can be done for extra 3 EUR, or for free if you book via Eurail.com (+2 EUR booking fee), or Ticket Offices of mostly all train companies in Europe like DB, Trenitalia or SNCB except ÖBB (3,50€). 

All this bookings can be done via ÖBB (using one way ticket option and interrail/Eurail as discount). 

Thanks so much for all the info @Angelo