Slightly off-topic, but it pertains to what was mentioned prior regarding power issues. It’s been my personal experience that running more than 1 RTL stick directly from the Pi’s USB ports is touchy at best - especially if running the FA Orange or Blue with their internal amplifiers. If you do so, make sure to plug one in the top rail, and the other into the bottom rail since the top and bottom USB ports have their own fuse. That said, it’s pretty tough to get them next to each other anyhow due to their width, but just the same.
I’d highly recommend a powered hub for dual RTL setups such as this - but use caution here: USB 3.0 chipsets are extremely noisy on the RF spectrum. Many wifi router manufacturers (the good ones at least) wont even incorporate USB 3.0 ports on their equipment due to the excessive noise - especially in the 2.4Ghz range since it really tosses a monkey-wrench in their router’s wifi signal. Find a good powered (5v/4A) USB 2.0 hub - they will be cheaper and there is zero to gain by using a USB 3.0 hub on a Raspberry Pi 1-3. USB 3.0 may not cause excessive noise in the 978/1090 Mhz range that you are talking about here, but noise is noise and if you have a choice, may as well caution on the side of quiet right? I guess this is especially noteworthy for those using wifi connections instead of wired. Personally, I think it’s best to shut the wifi and bluetooth drivers down at boot, but that’s not an option for everyone’s setup. If you are running wired, it be a good thing to look into. Just my opinion of course.
EDIT: Just found this - even better explanation of possible USB 3.0 issues - Note the chart from Intel’s whitepaper - nasty little spike just south of 1Ghz right smack in the middle of UAT. https://discussions.flightaware.com/ads-b-flight-tracking-f21/usb-3-0-broadband-interference-t36797.html