Old timer CB'er (waay back) and just picked up a UBC125XLT after popping over to Lakenheath and Mildenhall from my folks new place - have a couple of questions if I may?

I've got myself a copy of Scan125, and figuring that out to get my frequencies programmed in, been picking up a bit of London Control, RAF Odiham and Brize Norton as well as occasionally Middle Wallop. My first question is why the RAF airfields list two frequencies for approach and tower, is this for backup or is it military and civilian frequencies?
Secondly, my receiver came with a Nagoya NA-771 144/430, and a telescopic job. I bought a Watson W881 also as I'd read some good things about them - which should I run with out of the Nagoya and the Watson?
I am near Aldermaston and have been getting some decent signal from what I've mentioned above, even managed to correlate some of them with Flightrader24!
Thanks in advance!