Adding A Second Tank

[Crazybob]

Hey guys,
I have a 4 foot tank and stand in my living room that is like to add a second tank to. I plan on getting a piece of 1/4" plywood for the tank to sit on. I'm just nervous that
the added weight might be too much for the current stand as is and I would like some opinions if you would.

The stand is currently an "industrial" look which I was inspired from someone I saw on here a while back and it holds a 40g long. I would be adding a 20 long below it. I'll try to get a picture up but I'm on my phone right now and can't find a button for it.

 

[Crazybob]

Okay,
So here is an of images of my current tank and stand (sorry they're not great as they were taken with an old phone)

The legs are 4x4's and the cross-beams are 2x4's, with stainless steel brakets.

On a side note, does anyone know of a good way to put a piece of plywood under my current tank short of emptying it all out? (note: there is approximately 100-150 lb of stone and substrate in the current tank)

thanks again everyone!

edit: I would like to place the new tank on the lower crossbeams. After re-reading this post it doesn't seem to be clear that that is what I'm trying to do. Sorry for any confusion.