How to align two signals to have same 'off' value?

I am conducting an LDA classification between two signals over a timeseries.

These signals alternate between on and off in the following pattern: Signal 1 on for one second and signal 2 off, both signals off for one second, Signal 2 on for one second and signal 1 off, both signals off for one second, repeat (see below image)

The problem is, when both signals are off, the base current value for each signal is different (even though it is a tiny magnitude), as below - e.g. source 1 is 0.1*10^-8A when it is off, but source 2 is 0.8*10^-8A when it is off. You can see this difference in the log plot below:

The LDA classifier is much too sensitive to this difference, which is throwing off my classification.

How do I overlay/normalise the signals so that they both have the same off current?