I don't mind that, actually, and it's one of the things I like best about Dr. Temperance Brennan in Bones. She spends a lot of time in the lab but she also interviews suspects and goes to the crime scene and gets information about the crime and the victim that way as well.Even reading that made me twitch. True story: I had to teach my 26 year old sister what double dipping was, she'd never heard of it before. It was just us 2 eating something so I dont care but I had to explain not to do it in other company, oh dear. Just shows that not everyone is aware!
Someone mentioned cop shows - I hate in CSI and similar the way that they seem to do everything. You are a forensic scientist, get back to the lab. stop interviewing suspects and chasing them - why would you be interviewing suspects?! The show would work just as well as if they had another character who did all the interviewing.
About double dipping: It's something I try not to do, but it's also something I never thought about until I saw an episode of Seinfeld in which George Costanza is seen double dipping at a party and somebody yells at him about it. Oh yeah, not a good thing to do.