All LLD macros are extracted before processing LLD rule. That includes embedded macros like {"{#LLD_MACRO}":"abc"} and the macros defined in LLD rule configuration.

However there are no checks for duplicates and since they all are put in one vector that is sorted with unstable sort and later located with bsearch - there is also no defined priority which type of macro would override the other.

Steps to repeat:
1. import attached host template
2. send the following json (zabbix_sender -z localhost -s Host -k discovery -o "$(cat items.json)"):

[{
"{#L1}":"1",
"{#DES1}":"1",
"{#DESC}":"embedded macro",
"description":"lld macro path"
}]

3. Observe that item 'Item embedded macro' is discovered.
2. send the following json (zabbix_sender -z localhost -s Host -k discovery -o "$(cat items.json)"):

[{
"{#L1}":"1",
"{#DES1}":"1",
"{#DES2}":"1",
"{#DESC}":"embedded macro",
"description":"lld macro path"
}]

4. observe that item name was changed to 'Item lld macro path' despite the {#DESC} macro itself was not changed.