The fact is that this SMU's channels are sharing same LO and output voltages of the channels will be slightly different even if the same output was set. As an example when the PXIe-4141 is configured as shown in Figure 1, where DUTs sharing same GND. We have to consider that current can flow between channels through common LO.
For example Ch0 can sink current from Ch2, but as all channels are configured in source mode then this is not correct working regime for the device, which can cause the damage of the channel.
This is an example why it is not recommended
to create two bipolar channels.
The recommendation applies to all PXIe-414