Charles23

I have resolved the problem, thanks for your help. 
 
In the thermocouple picture above, the thermocouple will plug into the connector leading to the datalogger. 
The cables were connected reversed inside the connector, but also at the logger. I believed that this was not a problem, but fixed it regardless. 
 
Below is an image of both dataloggers recording the same data again. 

 
Thank you again for your help.