Hello,

With the input

```
{a,b,c#}::Indices("a");
ex:=1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a};
vary(ex,$X_{a}->A_{a}$);
sort_product(ex);
rename_dummies(ex);
{\delta{#},Z{#},X{#},B{#},K{#}}::SortOrder;
ex:=1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a};
vary(ex,$X_{a}->Z_{a}$);
sort_product(ex);
rename_dummies(ex);
\delta{#}::Accent;
ex:=1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a};
vary(ex,$X_{a}->\delta{X_{a}}$);
sort_product(ex);
rename_dummies(ex);
```

The output I get is

```
Attached property Indices(position=free) to {a, b, c#}.
1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a}
1/2 A_{a} B^{a b} X_{b} + 1/2 X_{a} B^{a b} A_{b} + K^{a} A_{a}
1/2 A_{a} B^{a b} X_{b} + 1/2 A_{b} B^{a b} X_{a} + A_{a} K^{a}
1/2 A_{a} B^{a b} X_{b} + 1/2 A_{a} B^{b a} X_{b} + A_{a} K^{a}
Attached property SortOrder to {\delta(#), Z(#), X(#), B(#), K(#)}.
1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a}
1/2 Z_{a} B^{a b} X_{b} + 1/2 X_{a} B^{a b} Z_{b} + K^{a} Z_{a}
1/2 Z_{a} X_{b} B^{a b} + 1/2 Z_{b} X_{a} B^{a b} + Z_{a} K^{a}
1/2 Z_{a} X_{b} B^{a b} + 1/2 Z_{b} X_{a} B^{a b} + Z_{a} K^{a}
Attached property Accent to \delta{#}.
1/2 X_{a} B^{a b} X_{b} + K^{a} X_{a}
1/2 \delta{X_{a}} B^{a b} X_{b} + 1/2 X_{a} B^{a b} \delta{X_{b}} + K^{a} \delta{X_{a}}
1/2 \delta{X_{a}} X_{b} B^{a b} + 1/2 \delta{X_{b}} X_{a} B^{a b} + \delta{X_{a}} K^{a}
1/2 \delta{X_{a}} X_{b} B^{a b} + 1/2 \delta{X_{b}} X_{a} B^{a b} + \delta{X_{a}} K^{a}
```

Is this behaviour expected? If yes, is there a way to obtain

```
1/2 Z_{a} X_{b} B^{a b} + 1/2 Z_{a} X_{b} B^{b a} + Z_{a} K^{a}
```

and

```
1/2 \delta{X_{a}} X_{b} B^{a b} + 1/2 \delta{X_{a}} X_{b} B^{b a} + \delta{X_{a}} K^{a}
```

instead?

In case it is really a bug, I run Cadabra 2.2.9 (built on April 7) on macOS High Sierra.