Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.7)
// Compass (v1.0.0.alpha.18)
// ----

@mixin color() {
 color: blue;
 .ie & {
   color: red;
 }
}

%color {
  @include color;
}

.sidebar {
  .title {
    @extend %color;
    // @include color; // uncomment this will create the correct code
  }
}
/* Why does above compiled code create two versions of selector order? */
/* --------- */

/* What I think should appear: */
.sidebar .title {
  color: blue;
}
.ie .sidebar .title {
  color: red;
}

SassMeister-output.css

.sidebar .title {
  color: blue;
}
.ie .sidebar .title, .sidebar .ie .title {
  color: red;
}

/* Why does above compiled code create two versions of selector order? */
/* --------- */
/* What I think should appear: */
.sidebar .title {
  color: blue;
}

.ie .sidebar .title {
  color: red;
}