hi bro warbird, I have indeed done so. Twice - with different sets of gals. "Shuangfei" session between my mistresses is probably about six seven times in total.
Its probably quite fun if you can pull it off well. I must admit here that I did not do so well with regards to the execution bit.
These are some negatives that you need to take note off.
In general before you embark on such any ménage à trois activities, you must know the characters of your mistresses. One obvious corollary is that Jealousy (I guess it a natural phenomenon as it concerns their ricebowl) will rear its ugly head.
QQ (a singer in a recently renovated KTV) & ZE were both under my patronage about three years ago. I brought them together for some "shuangfei" fun. What happens on the ground is really quite different from my expectations. My 'porno' based perspective were literally thrown quite asunder when both girls do not react well in terms of lesbianic interactions. Yes, there are several pleasurable elements such as one licking the shaft while the other covers the testes (or gives you a nice ass rim), the different array of new positions that avail to you - missionary while administering cunninglingus is nice ..
It is the aftermath that concerns me. QQ & ZE will invariably ask about each other. They would try to dig out information on how much I pay the other party (I gave ZE more). Every little gift or tokens was met with comments such as whether the other gets similar gifts. The simmering jealousy is palpable & it somehow detracts a little from each respective individual Love Wayangs.
To be fair, both frankly they tried to conceal this aspect, but I was quite sensitive to the nuance. There seem to be an 'invisible presence' of the other party. Gradually, because of that, a feeling of ennui (or "sian") with both of them crept in, the writing is on the wall with the relationship.
This being said, I know that 'shuangfei' can successfully executed. Mike & Hua have many orgy sessions with their mistress. In fact I partook in several of the debauchery sessions, including a particularly memorable one whereby we simulated a Roman orgy with the use of white bed sheets. Its eight gals and three guys with sex toys!
What sets my 'brothers' and me apart is that, they are able to ignore & dislodge the 'simmering' vestige of jealousy & rivalry between their mistress. They are able to set aside this behavioural quirks. For me, I just cannot ignore the underlying nuances of the inevitable unhappiness & jealousy of my mistress.
The reason why Mike & Hua is able to successfully handle this is probably them being more focused on the sexual dimension whereas I sometimes do place importance on the 'relationship & interaction' element (the 'sweet wayangs'). In this regard, I got to give props to them, they can allow their mistress to be 'shared'. I, on the other hand, still cannot do so until today.
And in response to your questions, yes, its a "common condom". Initially, its a change & replacement with every new position & gal, but later the same one is used for both girls.
