@Dev not sure what you've ordered before but rather than search for a "splitter" search for an HDMI matrix/switch. Below is one example but they come in a range of inputs/outputs and prices. I have 3 Sky boxes at work outputting to 9 TV's and use 3 matrixes to do this without problem.
FERRISA 4x2 HDMI Matrix Switch,4 in 2 Out Matrix HDMI Video Switcher Splitter +Optical & L/R 3.5mm Output,Support Ultra HD 4K x 2K,3D 1080P,Audio EDID Extractor with IR Remote Control https://www.amazon.co.uk/dp/B07MYRX22F/ref=cm_sw_r_apan_glt_fabc_9HVBWAX8E2H1VYEAWP2T
Also, how far away is the second screen? Without going into the finer details, cable length has an impact on the quality of the signal received at the second screen. Standard Cat 1 HDMI will get you to 5m without problems, Cat 2 HDMI cables will get you to 10-15m.
While bowing to @Saint1976‘s practical experience, I can’t see why a simple HDMI splitter wouldn’t work, as long as it works at all (not a given with Amazon stuff alas, and I pay a little more for Lindy devices and find them cheaper in the long run - or even the short run, given my hourly rate). A powered splitter might be better, though; these devices aren’t passive, and drain the incoming HDMI line a bit to power themselves if they dot have external power.
But I can see how critical the HDMI cables involved can be. Dropping the splitter out of the equation for the moment, can you successfully drive both TVs, one at a time, from where the Now device is?
If not, you have no chance of driving both at once.
If you can drive them individually, try putting the splitter on, but only connecting the HDMI lead from one TV at a time. Does this work, for one or both TVS, separately? If not, what happens?