I would rather it be 3x18 and 1x24 if only two mounts.
The 3x18 is the original and that seems to be a MUST.
2x18mm has NEVER made any sense to me since the advent of the modern 24mm D12.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !