Concurrent stimulus blocks conflict with most recently used channel beinf overriden.

[TheChymera]

With the following stimulus protocol:

onset	duration	frequency	pulse_width	amplitude	out_channel
10	10	0.2	1	1.0	4
30	10	0.2	1	1.0	5
50	10	0.2	1	1.0	4
50	10	0.2	1	1.0	5

during the concurrent stimulation blocks starting at 50s, only channel 4 will be active.

With this other stimulation protocol, however, during the concurrent stimulation blocks starting at 50s, only channel 5 will be active:

onset	duration	frequency	pulse_width	amplitude	out_channel
10	10	0.2	1	1.0	5
30	10	0.2	1	1.0	4
50	10	0.2	1	1.0	5
50	10	0.2	1	1.0	4

Given this record-related variability, I would conclude that there's some software issue at work here, rather than some hardware issue relating to parallel output element arrangement. @felixsc1 agrees :)