The new two wonders have brick and stone as their starting resources. This means that there are now two wonders that have brick (Petras and Babylon) and two that have stone (Gizah and Byzantine) as their starting resource. I believe that this makes these wonders (slightly) less valuable relative to all the others since the resource they provide is in greater supply overall if both of those wonders are in play. In a five person game if Gizah, Byzantine, Petras, Babylon, and Alexandria are all in play (for example) then I believe the Alexandria player (with a unique resource) has a distinct advantage.
I know it might be a minor shift in power but nevertheless I am considering a house rule that if the one of the wonders with brick (for example) is chosen then the other wonder with brick cannot be picked. Does this make sense to anyone else or am I crazy?
I think you might only be seeing this at the first level. The resources and their distribution and usage is really pretty complicated. See the resources sections of this fantastic post:
TL;DR version of the thread: Brick and Stone show up less on cards than other resources. But being shut out of larger quantities of brick and stone shuts you out of more cards than any other resources.