Rigidbody2D: Follow other Rigidbody2D strictly

I want to do something that actually sounds pretty simple: Make one Rigidbody2D follow another Rigidbody2D strictly, so that they have the same position, collisions and general behaviour.
Using rb2d.position = other.position; (rb2d and other both being of type Rigidbody2D and having the exact same configuration) inside FixedUpdate leads to other being behind rb2d not just visually, but also collisions differ:

In this picture, pink is other, and it collides at a different distance than rb2d.
I tried setting the velocity of rb2d in Update instead of FixedUpdate, I tried following in Update instead of FixedUpdate, I tried different ScriptExecutionOrders, nothing worked.
When I use transforms to realize the follow inside Update, there is no visually visible distance between the two, but the collisions do differ.
My use case is that I want to make a platformer with a player reflection following strictly on the x-axis but differing on the y-axis, but I ran into problems with the reflection glitching through platforms due to the physics differences to the player.
I attached a small sample project containing the logic from which the screenshot was taken.