Which model did you get? I'm not sure why there are two probes for the same spot. Since most of them appear to be analog (just turning the dial to set temp) there may be a slight range in temps between what it's reading and what it's set to.
Sorry ive confused you lol. 1 probe is for the thermostat but the other probe is from my digital thermometer.
Ive set the thermostat but wanted to check the temps were right so im measuring them with my digital thermometre. So the thermostat is set at 33c on the dial but the digital thermometre is giving me a reading of 37.7.
Ah OK. It's possibly a combination of accuracy of the digital thermometer and having the thermostat set to stay within a range as I mentioned. Perhaps setting the thermostat at 33 will tell it to keep the temps between 30 and 36 and the margin of error is 2 or some combination. The user manual for the model you're using might show what the range is set to by default. You could also double check the accuracy of your digital thermometer by putting it in an ice water bath which should read 0.
The B1HT manual doesn't specify what the temperature range is by default (it may not have one). Usually thermostats have a built in range that sits around your setting. One main reason for this is so that it isn't constantly turning your heat source on and off which could damage your light/heatmat/etc. The thermostat I have on my chest freezer (beer cooler) is set to keep it within a range of +/- 3 degrees (adjustable) so that it isn't constantly turning the compressor on and off which could damage it.
If you check the accuracy of your digital thermometer, you could tweak the setting on your thermostat to compensate.
Mine just run down to the battery unit below the tank so it doesn't get too messy. You could use zip ties or twist ties to pull them together a bit though. That's the common way of doing it with computer wires.