Players can summon multiple Mechanical Dragonlings using the engineering trinket and /duel

Originally reported: https://github.com/chromiecraft/chromiecraft/issues/874

#### WHAT CLIENT DO YOU PLAY ON?

- [ ] enGB
- [x] enUS
- [ ] other (specify)

##### FACTION

- [x] Alliance
- [x] Horde

##### CONTENT PHASE:

- [x] Generic
- [ ] 1-19
- [ ] 20-29
- [ ] 30-39
- [ ] 40-49
- [ ] 50-59

##### CURRENT BEHAVIOUR:

Players can summon a lot of Mechanical Dragonlings by /dueling and /forfeit right after trinket usage, the npc does not disappear after using the trinket again, it just summons another one, this can lead to abuse from players against open world pve fights.
The reason this is happening is that /duel resets all your cooldowns, so the same thing might happen for all the ''summon X npc to assist you in battle'' type of trinkets.

##### EXPECTED BLIZZLIKE BEHAVIOUR:

The guardian that is summoned after using Mechanical Dragonling should disappear and a new one should take its place.

##### SOURCE: Doesn't need source, it's obvious that it's a bug.

##### STEPS TO REPRODUCE THE PROBLEM:

1. get engineering and Mechanical Dragonling trinket
2. duel someone and use the trinket
3. /forfeit
4. repeat step 2 and 3.

##### EXTRA NOTES:

Item link: https://www.wowhead.com/item=4396/mechanical-dragonling

##### AC HASH/COMMIT:

https://github.com/chromiecraft/azerothcore-wotlk/commit/34da0cda5195dede48cb0406b23248330d6249cb

##### OPERATING SYSTEM:

Ubuntu 20.04

##### MODULES:

- [mod-ah-bot](https://github.com/azerothcore/mod-ah-bot)
- [mod-cfbg](https://github.com/azerothcore/mod-cfbg)
- [mod-desertion-warnings](https://github.com/azerothcore/mod-desertion-warnings)
- [mod-duel-reset](https://github.com/azerothcore/mod-duel-reset)
- [mod-eluna-lua-engine](https://github.com/azerothcore/mod-eluna-lua-engine)
- [mod-multi-client-check](https://github.com/azerothcore/mod-multi-client-check)
- [mod-pvp-titles](https://github.com/azerothcore/mod-pvp-titles)
- [mod-server-auto-shutdown](https://github.com/azerothcore/mod-server-auto-shutdown)
- [lua-CarbonCopy](https://github.com/55Honey/Acore_CarbonCopy)
- [lua-LevelUpReward](https://github.com/55Honey/Acore_LevelUpReward)
- [lua-send-and-bind](https://github.com/55Honey/Acore_SendAndBind)

##### OTHER CUSTOMIZATIONS:

None.

##### SERVER:

ChromieCraft

---
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Start by reproducing the issue with the Mechanical Dragonling, a duel, and /forfeit, then inspect the duel reset module's cooldown-reset handling. Check how summoned guardians are tracked and replaced after repeated trinket use. Done means repeated duel resets cannot leave multiple Mechanical Dragonlings active.

Written by the indexing model from the issue text.