Rotarius,
You may want to re-read the first question.
Interconnects are usually the low-level cables that carry a signal between source and pre-amp (or source and input to an integrated amp) or between pre-amp and amp.
Typically the cables used between amp and speakers are called speaker cables, not interconnect cables.
Yes, you can buy the same brand and sometimes the same model of interconnect cable and speaker cable, but there is no reason why you would need to use the same brand for both.
Enjoy,
TIC