All MK VIIs were made to the same specs. While different manufacturers may have slightly different variations on some details, you're not going to find any differences between them as far as inside compartments are concerned.
I have never seen that center divider before on a MkVII in person. I have one real MkVII and one replica, and neither of them had one of those things. Also, the real one doesn't show signs of having once had one.
If anyone cares to give the exact dimensions for the bag as a whole, its pocket placements, loops and drain placement etc. I'd happily work out a pattern for anyone who wants to [get a competant seamster/ess to] sew their own.
PM me or email me so we can discuss just what details I'd need and how to do it.
Enigmata
The divider on the original bags was used to separate the mask from the filter canister, so that is the correct format for unaltered originals. However, I have an older WPG repro which does not have the divider built into it. Personally, I like the center divider.