Yea, you'll need to make sure your plots don't overlap. If you plotted with the GUI wallet, then it is likely that it only accounted for a single machine... and thus the plots are overlapping.
I would suggest that you use different accounts for each machine if you're mining with the GUI wallet.
If you aren't using the GUI wallet, make sure you don't overlap your plots... i.e. this is the plot structure...
...
@dawallet, correct me if I'm wrong, but the GUI doesn't account for multiple computers, does it? I don't really see a way.
There is no advantage using the same Account for different machines, because all pools except pool.burst-team.us and burst.ninja punish miners that send a worse deadline than before.
Also you have to take care that your drive letters are different on each machine during plotting when you use the same account - due to logic of how the GUI calculates the plotting range. (That's the best idea I had a year ago to solve the overlapping problem)
I use the GPU plotter for plotting and I calculate range for the plots manually, I hope I did this correctly, but when I check overlaps with the plotter it shows no overlap. Hopefully that part should be fine at least.