2 Heat mats - on ONE printer

[GrantB]

OK Guys n Girls....
A little brain teaser problem I need to solve...
I have a 600 x 300 print bed & the bed heater mat has failed... I have two 300mm sqr heat mats & want to use these if possible...
BUT
I need BOTH to be regulated, but the printer only has means to detect one mat temperature.
I'm reluctant to run 2 mats in parallel with power turning on & off with a relay & just have temperature sensing on one of them to heat both, as it is possible that one may get hotter than the other & either let the print off the bed or over heat & burn out...
Is there any device that will control 2 mats from one regulation source.... or I have to bite the bullet & just spend tons of money & buy a new 600 x 300 heat mat at £75 each..

Any one done this, or have any interesting opinions ?

Keen to hear all the ideas people may have on this.
Regards to all
Grant B

[likimokalvis]

You could make device of your own to get input from 2 thermistors and average them, besides that I do not know any other way.

[james_i]

You could get a couple of cheap temperature controls and use the printers sensor to control print start