I was experimenting with building a rescue environment that has a different architecture than the system the rescue medium is build on. However, it does not work as it should, because most drivers are placed in the wrong folder. Since v7.2.4440 there are separate driver folders for each WinPE version and architecture (see
this thread). I would expect that if I build a 64-bit rescue medium on a 32-bit machine that the drivers would be copied to the 64Bit folder, but some are copied to the 32Bit folder.
The machine I tested on has Windows 7 x86 with Macrium v7.2.4473. If I build a WinPE 3.1 rescue environment I start with the situation in image #1. I then add drivers using the Update button for 4 devices as shown in image #2. After clicking OK the drivers are copied to the drivers folders. However most of them are copied to the 32Bit folder instead of the 64Bit folder. As a result the driver situation is still wrong (image #3). If I then look in the WAIKDrivers folder (mages #4 & #5) one can see that the drivers are mostly included in the (wrong) 32Bit folder and only 2 correctly in the 64Bit folder (VEN_8086_DEV_1C2D and VEN_8086_DEV_1C2 are the drivers for the Intel 6 Series/C200 chipset USB controller).
I have used the correct architecture when updating the drivers. I have also deleted the 32Bit and 64Bit folders before I did the test. The content of these folders is therefore the result of this test.
Using WinPE 10 something similar happens, so this issue seems not to be related to a particular WinPE version. In WinPE 10 I have only added the SI3132 driver, but that one is copied to the 32Bit folder.
On a Windows 7 x64 machine I have seen the same behaviour when building an x86 rescue environment, but then the reverse happened (drivers are placed in the 64Bit folder instead of the 32Bit folder). I did not collect more details about that machine, because what happened is similar to the behaviour on the Windows 7 x86 machine.
Edit: a few hours after writing the above observations I realised that the cause may be that when drivers are updated via the Update button, they are placed in the wrong folder if the rescue media architecture is different from the machine's architecture. That is consistent with images #2 - #5, which show that the drivers that are automatically copied by Macrium are copied to the correct folder. But because manual updating happens more when there is a architecture difference this issue occurs more than if the architecture were the same.