Is it of academic value to submit two papers describing two different but somewhat similar architectures? I'm going to submit two papers within the coming weeks. I'll be proposing two new architectures (one new architecture in every paper).

To sum up, the first paper surpasses the current state of the art. 

The second paper improves some criteria above the first paper however the overall result of the second paper would degrade compared with the current state of the art by a little.

I was wondering whether it is ethical and of any academic value to submit both papers or I must just submit the first paper?
You can submit both papers to one or two different conferences, as long as you have two new contributions in them.

Side Note 

It is advised not to cut the "meaty" part of a very nice contribution, into two or more different papers/journals. This sort of "slicing" put your future academic life at risk, because there are some academics that write many poor papers, by just slicing a contribution into different papers; and they are very well known for their "efforts". So, do not put your academic career at jeopardy, and think this through (i.e., contribution(s) you want to discuss in each paper).