I think we have discussed this before and I think modules do not register whether the signal came from timemark pin one or two.
Not true, the modules register the source, it should be easy to devide the file though.
The second issue is that it can only register one event per epoche, i.e. 200 ms if you run it at 5Hz.
So if you want to use to cameras you must trigger the cameras after each other. You should tigger the first camera and wait for at least 300 ms before you trigger the second. You could use an Arduino to realize this.
During post processing you need to have a script which divides the timemark list into two files.
We had an excessive discussion about that, I don’t know if @Stu74 implemented the solution:
If you need help and if you are ready to donate some serious amount of money to the Against Malaria Foundation for it I can help you with the script and the arduino code.