2x Portable 2x 8W fluorescent lights with incandescent mode (both 2x fluorescent mode)

Got both of these portable 2x8W EM module driven fluorescent lights that have a built in incandescent spotlight that uses a typical krypton filled torch bulb at the car boot sale

Both of them work as normal - showing them both on fluorescent mode. You can have the option to run 1x 8W tube but the most interesting (or more annoying) thing is that theres a horrific high pitched buzzing sound when you run them with 2x tubes but not with 1x. This happens on both of the portable lights