2nd Mic For One Source, things to consider Options

[Presto]

I'm intending buying a second mic, but as sometimes I'd like to use both on the same sound source, is there anything I should know before choosing, and then when using (such as phase considerations).

I have a Rode NT2 and am interested in the miniature DPA 4060 for its portability.

Any comments?

[Presto]

What I'm asking about is possible technical problems (such as phase) using 2 mics on the same source. While I'm at it, I should specify that I don't mean placing techniques for stereo considerations.

I can't say I'm not interested in the relative qualities of mics (for baby to adult voices, also various noises), but that's not what I'm asking about here.

(Off topic: I tried the SM57 with an imic, Recordit, and no pre! - the result was shitty. I now use the NT2 with an Mbox and Beyer DT250 phones and the sounds I hear seem undistorted, crystal clear, and loud - wonderful to me. Still, I'd need to borrow other mics to compare. We should push the Parisian MacMusians to get together with their various mics and to write us a comparative article)