Two heat pads = double the heat??

I already have a 8W heat pad on my 5.5g desert terrarium, but I feel that its not enough, and I have another spare 8w heat pad that I got from a friend sitting around.

If I put both of them, one on the long, and one on the short side of the terrarium, would that be overkill for my desert hairy?

When I stick my hand inside, I can only feel the heat radiating about a inch from the glass, I am unsure the temperature, but I doubt its even in the 80s.

Or should I stick them both on 1 side?

My scorpion actually spends most of its time with its body hugging the glass where I have the heat pad.

Stupid heating question I know :/

I think either way would be fine yr scorp will just burrow away from the heat if it was too much but it's highly unlikely heat marts will make too much heat lol, would be much better to use an infrared bulb with a thermometer to keep an eye on it

I have a IR heating 2 of my terrariums already, my shelf setup doesn't allow another lamp in there otherwise id be all over it