Hello Guys! I really need your help!

I sing opera and i am a lyric Baritone.
I' ll be recording lots of things as a Baritone and i really don't know how to do it but i know it's a little complicated.I have recorded rock,metal,pop stuff before but i know that this is a lot different.

I know, you're supposed to record opera singers in acoustically perfect concert halls, but I'm on a budget and all I have is my 8 x 10 home studio which doubles as both a control room and a live room. My goal is to record live vocals over pre-recorded orchestra karaoke tracks to famous soprano arias.

I'm new to the recording art. I've been recording a coloratur soprano that doesn't use much vibrato. I recorded two voices for a duet with the same soprano. At times she would get her voice to be more resonant (a characteristic of coloratur sopranos I guess). When that happens within a voice that is part of a duet I would get weird intermodulation with the other voice.