-By+a affects both primary and seconday labels

Hi,

I'm running this command in batch : 
```
[...] -Bxa20f10g10 -Bpya1Of1og1o -Bsya1Yf1yg1y+a-90 -BWSen
```

and the `+a-90` affects both primary and secondary frame (only secondary wanted).
I tried 
```
[...] -Bxa20f10g10 -Bpya1Of1og1o+a0 -Bsya1Yf1yg1y+a-90 -BWSen
``` 
but it doesn't change anything, only the last call is taken into account.

Thanks,
Guillaume