Have one of them taller (or more so frontal) to emphasize a hierarchy of volumes.
The smaller volume may be smaller and identical or the complete opposite.
Either way, it needs to compliment the larger volume whether in submission or its blatant antithesis.
In architecture, there is often no distinguishable difference. It speaks the same...
We can also call this the 'little bro' scheme.
It is human nature to be able to quickly comprehend a familial hierarchy in a conversation...
like calling out 'little bro' in slang rather than describing an architectural entity in relation to another.
So fun tip;
When describing a 2 tower scheme, it comes out friendlier to call out familial terms
e.g little brother, son, cousin, mother etc
C4D + Octane + PSD files available to for download! This is my first. Have fun!