Two synthetic survivors spawning at once (?????)

## Testmerges
#12824: 'Bundles Wound Overlay Updates' by fira at commit 6b48f2d5f1
#12537: 'Atlan Station - Groundmap' by oceany-a11y at commit 774eef601e
#12618: 'Vanguard Passive Shield no longer regenerates when UNCONSCIOUS or INCAPACITATED, FLOORED, updated strain description.' by Venuska1117 at commit 813c96e27b
#12627: 'Tyrargo Rift (2) - Various Alterations' by Steelpoint at commit dbc4496523
#12947: 'Revert "Working multiz tacmap, round two, extra buttons"' by Rain7x at commit ea384007a4
#12793: 'Explosion Waves: Visual update and Backend rewrite' by fira at commit 95f326f509
#13027: 'Add Multi-Z handling to get_line' by MistChristmas at commit 7dee321554
#12968: 'M44 Combat Revolver Buff' by AnCopper at commit 6f065ca883
#13032: 'Some Role Authority Cleanup' by Drulikar at commit e0b6b5312a
#12986: 'Smartgun Ability Overhaul' by AnCopper at commit a2eefa45e4
#13046: 'Changes valkyrie rage usage style' by Red-byte3D at commit b81e8e1b9b

## Round ID
36144

## Description of the bug
I rolled Synthetic Survivor on Sorokyne Strata, one synthetic player spawned as the 121st insert synthetic, and I spawned as a regular sci-variant synthetic

## What's the difference with what should have happened?
I believe the game should NOT spawn two synthetic survivors since the slot was always 1

## How do we reproduce this bug?
Honestly, I have no idea.

1) have 2 people roll synthetic survivor
2) Possibly force a survivor insert, in this case 121st
3) See 2 synthetics spawn, an insert and non-insert synthetic

## Attached logs
```
N/A
```

## Additional details
- Author: Szymonalex1231
- Admin: the thepolynomer
- Note: None

No source files, tests, or logs are named. Start by tracing synthetic survivor selection and the survivor-insert spawning path, then reproduce the Sorokyne Strata scenario with two synthetic survivor rolls; done means the slot limit is respected and the two-synthetic outcome no longer occurs.

Written by the indexing model from the issue text.