I was thinking of plane surfaces, but if their altitudes are different, I guess it’d be possible.

Wdym?

Equal sides in a triangle are only possible if the corners are equal. So, 60⁰ each.

But its height cannot be half of base because of the same Pythagorean theorem

(1,5)²+(1,5/2)²=2,8125

sqrt(2,8125) ≈ 1,677, which is half of a diagonal

So, we get 4 sides that are 1,5 in a parallelogram, but diagonals are 1,5 and 3,354, as opposed to both being 1,5 as shown on the picture

TL;DR: Won’t work because Pythagorean theorem