New Windows 10 Insider Preview Fast+Skip Build 18922 (20H1) - June 19 Insider

CountMike said:

It could be done from MSCONFIG.exe but I prefer using EasyBCD EasyBCD - NeoSmart Technologies to make a BOOT menu on primary disk
Attachment 238245

It can also be done from Macrium Reflect's rescue disk.

Build 18922.1000. I couldn't download via WU an update for Windows Security. It just sat at zero downloaded.

I had this option turned on:

I turned off "Allow downloads from other PC's" and the download worked. I don't know if anyone else has had this problem. It could be mine only. Thought I'd let others know just in case. I tried the fix for WU on this website first but it didn't fix the problem

CountMike said:

It could be done from MSCONFIG.exe but I prefer using EasyBCD EasyBCD - NeoSmart Technologies to make a BOOT menu on primary disk
Attachment 238245

Perfectly correct in my experience. (Some of that experience has been hard-won and painful.)

Update on my clean Install of 18922.
I removed the NVMe drive that had the1903 installation (it was under the sound card, so that had to be removed also.)
I then clean installed 18922. Replaced drive and sound card. Disk Management shows 3 partitions on the drive with Insider. (Macrium also shows the MS reserved partition at the front of the drive.) Used EasyBCD to add the 1903 installation to the boot. Both systems boot successfully. Many apps to re-install on Insider now.

If I have the setting animate windows when minimizing and maximizing on give it gives me a black screen flash after login