Why did Teseo-LIV3FL didn't support GLONASS and BeiDou at the same time?

[AFidi.1]

I'm trying to activate all constellation on my Teseo-LIV3FL module and then it says Glonass and BeiDou constellations aren't supported at the same time, but why? The docummentation didn't explain any further about this issue.

[Tesla DeLorean]

Likely because it has two RF down converters and GPS/GALILEO, GLONASS and BEIDOU primary bands together would need Three​