Despoiler and others xeno can combine their acids and melting guns together at the same time

### Testmerges

IDK

### Round ID

doesn't matter

### Description of the bug

So as I write, Despoiler and others xeno can combine their acids and melting one gun and maybe every other's thing together at the same time, so your weapon are melting from2 different acid and It is destroyed in 10 seconds, in two ticks at once.

### What's the difference with what should have happened?

If one acid is on a weapon or other item, you cannot use another until the first one disappears. Or the stronger one must cover the weaker one, and the process must start over.

### How do we reproduce this bug?

1. some xeno use acid on weapon
2.Desp comes and use his acid on same weapon.
3. The first acid causes damage to the weapon
4. The second acid causes damage to the weapon

### Issue Bingo

- [x] Issue could be reproduced at least once
- [x] Issue happened in a recent (less than 7 days ago) round
- [x] Couldn't find an existing issue about this (https://github.com/cmss13-devs/cmss13/issues)

Start by reproducing the issue with two xeno acid attacks applied to the same weapon or item, following the listed steps. Trace the acid application and damage entry points used by both attackers. Done means a second acid cannot apply while the first remains, or the stronger acid replaces the weaker one and restarts the process.

Written by the indexing model from the issue text.