Reproduction steps:
1. Open project attached (InstantiateBug).
2. Open scene "Scene"
3. Press Play.
4. Check gameobject "Parent" children's position.

Expected result: Children will have identical position.
Actual result: Children have different position.

Notes: Instantiate(Object, Transform) function started using local position by default in 5.5: "Using Object.Instantiate(Object, Transform) will now use the Object position as the local position by default."
Instantiate<T>(Object, Transform) was not affected by these changes. Due to that, those functions work differently.

Reproduced on: 5.5.0f3, 5.5.1f1, 5.6.0b5