How to add second receptacle to the same line?


I know it sounds rudimentary, but I'd like to make sure I'm doing it right.
I have two dedicated power lines with one duplex receptacle on each, that I want to add another two duplex receptacles to.
I have an idea, but not sure it's the right one. I don't really want to call an electrician for that. I installed receptacles before, so that shouldn't be a problem.
thanks in advance
maril555
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Mental? ok, but you make sense. (sometimes sadly lacking in these forums (fora?)
Mental,
Maybe in a strict technical terms it's not dedicated, but it is dedicated as far, as nothing else is on the same line