I read this thread before my first cup of coffee, so this may be a repeat:
Omnis on a stand = Monophonic Recording
Omnis need wide separation (a few feet or more) for Stereo
Or one of Moke's Jecklin Disker things, or a head between them.
Not that Mono is inherently bad, it's just not Stereo.
I'll take a full, well-balanced Mono over a thin or phasey Stereo recording anytime.