duplicate toggles on forms with multiple extends@ values

i have a template form that i want to extend multiple other forms. so i referenced the forms to be extended to the its blueprint. i've done many variations — template3.yaml:
```yaml
extends@:
- template1
- template2
```
```yaml
extends@:
- type: template1
- type: template2
```
```yaml
extends@:
- type: template1
context: blueprints://pages
- type: template2
context: blueprints://pages
```
including also variations with `@extends`, `'@extends'`, and `'extends@'`. always with the same results. — the template3's toggles appear as many times as there are `extends@`.