Some people are so obsessed with theory that they hardly dare make a recording for fear of transgressing the laws of audio.
But as we know, some laws are there to be broken (that's so you get your 'badboy/badgirl' kicks without doing any serious harm to anyone!).
When it comes to audio, there are no laws other than the laws of physics. The so-called 'rules' are merely guidelines. Whatever sounds good is good.
If you want to record in stereo, then it is best to have two identical mics. Some would go so far as to insist on mics with adjacent serial numbers (and they'll always use the odd numbered mic on the left channel).
This is good, because the two halves of the stereo sound field will be picked up equally and the recording will be as well balanced as the performers and the acoustics.
But just because you don't have two matched mics doesn't mean you can't record in stereo. Try it – point one mic to the left and the other to the right – see what it sounds like.
If you thought the result was going to be terrible and totally unusable, in all probability you will be proved wrong. In many cases you will hardly notice the difference.
There are situations where the difference will be marked – if you use a capacitor mic for one channel and a dynamic for the other for instance. But don't let it stop you. There might be some level matching and EQ balancing to do, but you can still get a good result that no-one is going to quibble about unless they know how it was achieved.
The worst case scenario would be if one mic was out of phase with the other. This means that for sources in the center of the stereo image, the cone of the left hand speaker is pushing out while the cone of the right hand speaker is pulling in, and vice versa.
But this can happen with any two mics due to incorrect wiring. By convention mics are wired so that an inward pressure on the diaphragm results in a positive electrical voltage. Simply invert the signal of one mic back again, using the phase button or by rewiring a cable, and all will be well.
The thought occurs that if you do have a matched pair of mics, you have probably never even considered using dissimilar mics for stereo.
Well now is the time to try it! You may be surprised at what you hear.