ATIS and ATC Simultaneously in FSHUD!

When I start FSHUD I am hearing both ATC instructions and ATIS at the same time. It’s chaos. I don’t think this occured when I first tried FSHUD and it may only be with addon aircraft, not default (I need to test that further). I was able to kill the ATIS by changing COM 1 frequency in an addon plane but I want to figure out why this is even happening. Why would I get ATIS unless I physically select it?

Probably your COM1 is set to ATIS and COM2 is set to another ATC station.
Then you hear both COM’s on the same time (as it happens in real world).

That makes sense, but usuing the default ATC (not that I like the default ATC) it didn’t happen.

Because default ATC doesn’t simulate same time multi COM channel transmission.
Which is part of real world experience.