For me, a rate of another lady has zero bearing on me.  
A gentlemen may want to see a massage girl and she will more then likely charge less then I do.  
Does she think her rate is unfair because she offers less services? Doubt it. We all do what works best for us.  
For a good analogy, when I go to yoga or the gym I'm not looking at others and saying, I cannot stretch as far as that girl or I cannot dead lift as much as that guy. It's not a competition.  

For myself, I often wonder why some girls do not charge more for the services they offer (ahem-Portia and Elan both deserve raises IMO).  

I've never been jealous of another provider's rates. Great question OP.  
Soft and sweet,
SG

The only thing I check...

Is that the number or email matches the providers profile so I don't feel like its a nosey wife calling! The reference's rate has no effect on mine.  

x

Haven't had it cross my mind...

But then again usually when I get requests- I'm not just sitting at home with time on my hands...I probably wouldn't even  know the other gal's rate.  
I may remember that he visited with her & mention what I like about her(if I know her) the next time I'm with him.  

I never want anyone to feel like they can't share that stuff with me. However it's a fine line & I don't want to intrude by asking too many questions either. I take great pride in visiting with my gentleman friends & there is no room for feelings of jealousy in hobby world.  
reference checks are about safety & nothing else.  
I believe the pool of hobbyist to be infinite. And sharing is caring! =)  
Smile big, smile often,  
~Mind

I never get offended, when a shared client is paying me and another lady different amounts ..

I never get offended, when a shared client is paying me and another lady different amounts , during the whole "reference check part."  However , I have heard a few ladies complain about it , like during provider-to-provider discussions.   This is "some other girl's problem".  It is not my own personal problem.  I also think that it is my job to push my own "value" up higher , if I want to get a $ 100 raise !!!  Like , if I am getting underpaid , it is mainly my fault + I need to work on boosting my price point , if that is something I am in the mood to work on ...   Also , I am well aware that there are two different work models happening , like a provider that charges over $ 1000 per appointment is working less often than I am.   We might make the same amount of money , but I am seeing more clients than she is seeing.  So , I feel no resentment over this one !!!  

The thing that burns me personally , is when I do a double with another lady , and I work way harder than she does , during the session , and her pay is like double or triple mine + We are working in the same room !!!  That will annoy me !!!  I try to only do doubles with ladies in my own price point , for this reason.   OR, if a provider has a lower rate than me + We are doing a double , I will be charitable and fair and give her 50 % of the pay.