When I look at direct TGV trains from Charles de Gaulles to Nice on May 4, 2011, it seems like there are 2 trains leaving at 11:42 going directly to Nice with no stops. The train numbers are # 9826 and # 5164. The only difference I can see is that # 5164 is a duplex train. Yesterday I reserved 2 Prems seats on # 9826 in 1st class at 40 Euros each. Seats in 2nd class were 90 Euros for 2 seats. I booked on the TGV Europe site.
My question I guess is, are there really 2 TGV trains to Nice leaving at the same time, both trips are 6 hours and 22 minutes and both arriving into Nice at the same time? Thanks for your help.

they show trains for the next day. Those are two different trains based on the date. They could not run two trains at the same time on the same track, of course.

09825 is for may 5th, I believe, and 05164 for may 4th

The time schedule shows you that and if you clicked to buy it you would see the date, hope you would notice. The 9826 train says "jour+1" on it if you ask for trains for May 4th, because it is on may 5th.

So check your ticket and see what date it is. When I checked to buy that train, it clearly said it was for may 5th.

Thank you for your quick response. Our tickets have the Depart 04/05 a 11:42 de Charles de Gaulle 2 TGV
Arrivee 04/05 a 18:04 a Nice City
TGV 9826

Train 9826 goes from Brussels to Nice. Train 5164 goes from Lille to Nice. The two TGVs are joined at Charles de Gaulle and continue as one train to Nice. Therefore, from the airport to Nice, passengers can reserve seats in either train, but you cannot walk between the two parts of the train. Each part of the train will have a bar.
TGVs often run this way. From Paris to Brittany, for instance, there are 20-carriage TGVs to Rennes where the train divides: a ten-car train goes via northern Brittany to Brest, and a ten-car train goes via southern Brittany to Quimper.

Thank you very much for your answers. Do both trains have the same car number? Is there a way to tell if you are in the Car #4 of 9826 or Car # 4 5164? Pardon me if this is a stupid question. This is our 1st TGV experience and 2nd train experience from CDG.

<<They could not run two trains at the same time on the same track,>>

Actually the SNCF does do this. They typically run a regular TGV which is physically connected to but not otherwise accessible to an iDTGV train which follows. The two trains have different numbers, different compositions but otherwise the arrival/departure times are identical.

I find just as Christina points out, the 9826 departs on May 5th, the 5164 departs on May 4th.

There will be no confusion over carriage numbers. If they are eight-car trains, one will have carriages numbered 1-8 and the other will be 9-16. At the station there are signs to indicate the layout of the train to tell you which part of the platform to wait.
In this case, train 5164 from Lille arrives at Charles de Gaulle at 1132; train 9826 arrives from Brussels at 1136. Train 9826 must therefore be in the rear. The combined train leaves at 1142.

Also, I have found in most cases where there are two distinct but connected trains, there are always train personnel at the quais to make sure you get to the right car on the right train.

yeah, I see that, it is weird. I don't use TGV-europe, only the main voyages-sncf website and they seem to have different info on those trains. Well, as long as you have a train ticket with that date on it, I think you are okay. Sometimes they do give two different numbers to the same train, though, but usually that is for a TGV and iDTGV number or something like that, and then it will be different cars. I've never seen two diff. train numbers, both for a regular TGV, for the same train. Maybe one is for the upper deck and the other not.