JavaScript + Python 2 + Japt, 3 languages, 132 bytes, score ~= 0.205

A="`i96d)p2`i96d)p2";1//2;A=1 S="S=%s;console.log(S,uneval(S))";A//2;S="S=%r;print S%%S";""" console.log(S,uneval(S))//""";print S%S 

This prints

S="S=%s;console.log(S,uneval(S))";console.log(S,uneval(S)) 

in JavaScript (only in Firefox),

S='S=%r;print S%%S';print S%S 

in Python 2, and

`i96d)p2`i96d)p2 

in Japt. (Test it online!)

JavaScript

This is what JavaScript sees:

A="`i96d)p2`i96d)p2";1 S="S=%s;console.log(S,uneval(S))";A console.log(S,uneval(S)) 

The first line is a no-op because A is not used in any way. The second line sets S to the string S=%s;console.log(S,uneval(S)), and the third prints it after replacing the %s with the unevaled representation of S (just S wrapped in quotes). The result is a quine in JavaScript.

Python

This is basically what Python sees:

A="`i96d)p2`i96d)p2";1//2;A=1 S="S=%s;console.log(S,uneval(S))";A//2;S="S=%r;print S%%S" print S%S 

The first line is pretty much a no-op; the only important part is the A=1 at the end. This turns A into a number so that the integer division A//2 on the second line doesn't throw an error.

The second line is mostly the same way, except it sets S to the string S=%r;print S%%S. The third line prints S after replacing the %r with the raw representation of S (just S wrapped in single-quotes). The result is a quine in Python 2.

Japt

This is the JavaScript code the Japt interpreter sees:

A="`i96d)p2`i96d)p2";1//2;A=1 S="S=%s;console.log(S,uneval(S))";A//2;S="S=%r;print S%%S";"","\nconsole.log(S,uneval(S))//","";.p("r".i("n".t(),S%S)) 

As you can see, it's mostly the same as the JavaScript answer, with one main exception: the last two lines are combined. As a result, this is what the interpreter actually sees:

A="`i96d)p2`i96d)p2";1 S="S=%s;console.log(S,uneval(S))";A 

The first line sets A to the Japt quine, and the second sets S to part of the JS quine. In Japt however, only the last expression is sent to output; this is A, so the output is `i96d)p2`i96d)p2.