Wow, in another post something was mentioned about a concertina that uses the same reeds for the push and pull. This really got me curious, so I started experimenting with it. I actually came up with something that worked and was amazed at how simple it is.
I don't know if this sort of thing is common knowledge or not among builders, but I can understand why it's not used often. It takes up about the same amount of space as having 2 reeds(maybe more space?). And also, the push and pull seem to have two distinctively different tonal qualities(although that might be fixable).
On the other hand it may have some advantages, such as having half the amount of reeds to retune.
Eitherway, it was interesting to experiment this and it feed my curiousity.
I can post more info on this if anyone is interested.