I believe you are looking at are French divisions, which are given to the player through the scenario. Their names are written into the scenario, and not generated through some automatisms of the game. If you buy new division units they will get a names like "1er Divsion d'Infanterie", "2e Divsion d'Infanterie", etc. If you build an old-style division, by giving a leader division command first and then adding brigades, the division will be named after the leader.
There are a couple of CW2 scenarios, in which brigades are named 1st Brigade, 2nd Brigade, etc. and their divisions are named 1st Division, 2nd Division, etc. if they start the scenario inside a corps with each corps having one 1st Division one 2nd Division etc., but these are names written into the scenario.
The problem with this is if you reorganize your divisions by moving brigades from one division to another, and corps by moving divisions from one to another, then the numbers don't match up at all any more. I've wound up with a corps with 2 3rd Divisions and the 3rd Division had 3 1st Brigades