Burn engine not detached from managed bootstrapper

[petm2022]

I build a managed Wix bootstrapper (setup.exe) using Wix 5.0.2. It is signed with SignTool.exe and it works fine.
In the document Signing packages and bundles I can read that I also need to sign the embedded Burn engine.

The documentation writes that I must detach the engine, sign it, reattach it, and sign the bundle.

If I take my signed setup.exe and detach the engine using command Wix burn detach setup.exe -engine burnengine.exe the two files setup.exe and burnengine.exe are binary equal.

Is that a bug in the detach tool or because it is a managed bootstrapper?
If I create a standard bootstrapper and do the same, there is a difference.

I tried with Microsoft’s VC_redist.x86.exe and could see that the engine was not signed.
So, another question is why must the engine be signed?

[petm2022]

Main question answered here: Uncompressed bundle doesn't need two-step signing