Yes, you might assign them different numbers in a consist, but there is little point unless you want to use the B unit with another loco sometime. If you will only be using the B unit with its matching A, there is no point. Just assign them the same number.
Assigning different numbers would have a point if the B unit had some functions that you wanted to control while in the consist----and I can see that only if you had sound in it (which I do in some of mine). You have no light function to control etc. etc.
On some of my matching pair that I always run together, I connect them with a drawbar anyway. It is prototypical and and a better link----esp if I want the diaphrams to mate properly.
You must also take some time to speed match them. I have been working on speed matching all mine this month and find that even identical units, let alone As and Bs, even with identical decoders can vary significantly.
Try to get them matched at all speeds too, not just top speed. Getting their top speeds equal is actually the easy part. Getting the mid speeds and starting speeds can be trickier....not to mention that one often runs at a different speed in reverse, but I'm not getting into that.
[Or you may get that lucky set that is darned near perfect already.]
Sorry if the second part is unsolicited advice. Just me noodling away on the computer this evening.
I would give them different numbers and run as a consist, that will give you more options for operation of both of them. Unless you plan to keep them together semi-permanently then either would work I suppose.
ive just purchased proto f7 a @b units,plan to run together should i programme on one number or program both different numbers and run as a consist ,i run nce dcc trev down under.