"Extract subexpression to variable" reuses variable name

1. Have a trivial line in a source file:

       int i = 1 + 2 + 3 + 4;
   

2. Select the first half of the sum, e.g. the first two summands and the plus sign.
3. Press Alt+Enter and select "clang: Extract subexpression to variable" from the popup menu.
   Works as expected:

       auto placeholder = 1 + 2;
       int i = placeholder + 3 + 4;
   

4. Select the second half of the sum, e.g. the last two summands and their plus sign.
5. Press Alt+Enter and select "clang: Extract subexpression to variable" from the popup menu.
   This reuses the same variable name creating a compile error:

       auto placeholder = 1 + 2;
       auto placeholder = 3 + 4;
       int i = placeholder + placeholder;
   

This should use distinct variable names.