When using the transmission queue by setting simultaneous transmissions to "local files only on the same devices", then starting 3 separate copy jobs, \#2 and \#3 are initially delayed, so far so good, but after \#1 finishes, \#2 and \#3 start simultaneously copying even though they share a source / destination HDD. In fact, when \#1 finishes, all other jobs that waited for \#1 are started.