I believe that there are some surge protectors and power filters that provide not only a drain for spikes and other oddities outside of the 60Hz sine wave, but first resist them. If a product like the Tripplites you have purchased has multiple stage filtering, similar to a loudspeaker’s crossover that passes lower frequencies to the woofer while first blocking, then subsequently draining, then perhaps further blocking, then perhaps further draining high-frequencies, the Tripplites may provide no significant load on the irregular wave provided by the UPS in battery mode. Perhaps the Tripplite web site will have some details to offer on the models you bought.

If I were using a $7 power/surge protect strip from MalWart after the UPS, I would be tempted to cut the connection to the MOV component so that the strip functions only to distribute power.

From this web page :

“Roughly speaking, surge suppressors work by detecting over-voltages, and shorting them out. Think of them as voltage limiters. Line filters usually use frequency-dependent circuits (inductors, capacitors etc.) to "tune out" undesirable spikes - preventing them from reaching your electronics.

“These devices come in a very wide price range. From a couple of dollars to several hundred. We believe that you can protect your equipment from the vast majority of power problems by selecting devices in the $20-50 range.

“A word about grounding: most suppressors and EFI filters require real grounds. Any that don't are next to useless.”