Standard -p command-line flag no long accepts format parameter

### Problem

When using the `-a`, `-p`, and `-F` options to the duplicates plugin simultaneously (and combined) the output varies depending on the ordering.

Running this command (and various other permutations):

```sh
$ beet duplicates -apF
```

Led to this problem:

```
NO OUTPUT
```

Combining the arguments in various other orderings work fine, for example:

```
$ beet duplicates -Fap
$ beet duplicates -a -p -F
```

Note that the output was also as expected when listing the options individually. This seems to be a bug in argument parsing.

### Setup

* OS: macOS 10.15.7
* Python version: 3.8.5
* beets version: 1.5.0
* Turning off plugins made problem go away (yes/no): N/A

My configuration (output of `beet config`) is:

```yaml
directory: ~/Music/Beets

import:
copy: no
write: no

plugins: badfiles duplicates info missing
missing:
count: no
total: no
album: no
duplicates:
album: no
checksum: ''
copy: ''
count: no
delete: no
format: ''
full: no
keys: []
merge: no
move: ''
path: no
tiebreak: {}
strict: no
tag: ''
```