I've been washing bi-weekly for a few months now (instead of my normal weekly routine) and I clarify everyother wash, I feel that my hair and scalp are getting clean with my current regimen, I just wanted to use up some of these cleansing conditioners I have.
I use to love cleansing conditioners but like a year or so ago they all just seemed to stop working, I felt like my hair and scalp was not getting clean enough. I was figuring they might work better as a second wash.
Maybe I should just leave well enough alone.
ETA: To answer your question "is there a reason you want to cleanse twice?" Not really, I've always cleansed my hair once and let whatever I'm using sit for awhile, but I've been programmed to think one lather is not enough, even though my scalp and hair feels clean with one lather....