Qestions on Mixer input

1) when lna single output,one of double balanced mixer input is grounded and the other with signal ,
will it deteriorate the system performace ? ( QPSK signal)
2) two mixer input with different amplitude (1dB or so) or phase not exactly 180.
it will apparently degrade the performance. I think it can be fixed in digital algorithm
.right?

The LO and RF (signal) port are typically dc shorted. But of course, is not shorted at the operating frequencies.

Using two mixers in parallel as some sort of demod scheme will produce phase and amp error, but can be fixed in baseband. I'm not a baseband guy, so don't ask me how.

Rod