Hi listener

To answer you question, as long as the LCR speakers are matched you are ok.

The surround channels do not have to be the same brand to get great sound so long as they are properly positioned and level matched in output.

Even in a system with the same speakers all around, there will exist timber differences due to phase, acoustics and interference with your seating choice. The “head related transfer function” also plays into differences at a given angle.

Playing pink noise in each channel will quickly reveal differences, even in a matched system.