Steps to reproduce:

1. Select a host that has Discovery rules.
2. Go to the list of Discovery rules.
3. Clear the page filter.
4. Find a Discovery rule that has a master item (example: Linux by Zabbix agent: Get filesystems: Mounted filesystem discovery).
5. Click on the master item link see configuration form.
6. Observe browser console.

Result: Browser console shows the following warnings:

[DOM] Found 2 elements with non-unique id #context
[DOM] Found 2 elements with non-unique id #label-type 

Expected:
Each element in the DOM should have a unique id. Opening the master item popup should not create duplicate IDs.