Mom would be in the early to mid thirties and the daughter would be 18.

I'm sure the daughter would be UTR and the mom might offer doubles to regular clients only.

I fucked a mother and daughter separately wildly (civvie situation)

The  blonde Mother with big fucking implants had hit on me at work dozens of times and made no bones about the fact she wanted to fuck me. So I got drunk and succumbed to her advances.  I fucked the mother every which way  (who was my boss at the time) and the Mother told her sophomore college daughter I was hot and a great fuck so Mom hooked me up with daughter. Co-ed sophomore was into bondage, and made me buy handcuffs and duct tape.  Daughter was living with Mom, and was  Mom at home while I cuffed and duct taped her tight blonde kid. I fucked her in every orifice BB (including her ass) , and no question Mom (my boss) heard daughter screaming and her head hitting the wall in some kinky sex. We did this all  night. I removed the cuffs and duct tape and we crawled out of bed and went into the kitchen in the morning, and MOM (my boss) was waiting with a smile asking us what we wanted for breakfast? And said "sounded like you two had FUN last night".  I was bit freaked out, but Mom was showing her tits and made it clear daughter would be sharing ME with her.  It was a bit surreal, but a wild summer. I fucked both Mom & daughter co-ed for 4 months, but never together. I had suggested it, but Mom would have none of the doubles team. I couldn't argue -- she was my BOSS.   LOL    

That pops up in New England periodicalky. They are a bit rough looking though.  They have been reviewed..

There was a pair in Atlanta, Deanna and her daughter (can't remember her name).  I don't know if they worked together or not and think the daughter may have retired, not sure.

Not at the same time

When I was 18 ,  a 18 year old part time GF FWB  introduced me to her Mom .
Not long after , I had a few secret rendezvous's  with the 35 year old MIDF , at Mom's request .

 I had a  duo offer from a  stripper friend and her Mom  a few years back .  The stripper was 30 , I didn't ask how old her Mom was , I left before I changed my mind , or another drink ,  since both of them had too much road wear IMO .

One traveling gal I have known for many years had a scheduler who was very nice, but very chatty and insisted on trying to get to know me somewhat when we spoke.

I found out many years later that this scheduler was the gal's mother.  Her deal with her was that if she wanted to see guys, her mom had to OK them during the screening process to weed out anyone who she thought could be trouble for her.

We all three met in fact just recently when her mom offered to drive us all to the airport for me to catch my plane.

It was a triffle awkward at first, but we all warmed up to each other eventually.