@veti After some research I've found that both of my thermistors had the wrong beta coefficient on Marlin since e3d says to use the TEMP_SENSOR 5 (wich has 4267 K beta value) and that my heatbed thermistor looks like a cheap chinese one with 3950 beta value. So I've put the e3d preset B4725 and C7.060000e-8 for the hotend and B3950 C0 for the heatbed on RRF.
I guess the manufacturer didnt care about the +-150 difference on both thermistors and just went with TEMP_SENSOR 1 on Marlin.