Cannot add a second account in version 3.10.0 (macOS)

I have defined several users, one for each of my two MacBook Pro’s, one for my iPhone and one for my iPad. On each MacBook Pro the Nextcloud sync client ver. 3.10.0 (macOS) is installed, and on each of the “iToys” the appropriate Nextcloud.app. Although I am the sole user on all devices, I like to employ device-specific accounts (“logins”, e.g. RRL-mbp15, RRL-mbp16, RRL-iphone, RRL-ipad) so that I can see from the logs on which devices I did what. In additions to the device-specific accounts and the admin account that was created by OwnCube when they created my Nextcloud installation on their servers, I have created my own admin account, RRL. I use it to create folders and shares.

My problem is this. On the MacBook Pro 16" I created the first account in the sync client using the login for RRL. I did this because I was going to create the folder on the server that would then be synced with the MacBook Pro 15" and made available to the iPhone and the iPad through the Nextcloud.app. That all works fine, and now I wanted to create a second account on the MBP 16" to use RRL-mbp16. The process seems to go as expected. I’m asked to specify the Nextcloud instance, but instead of then being asked to login, the login dialog is skipped and I’m automatically logged into the existing account. That is, I’m automatically logged in as RRL, I cannot manually login as RRL-mbp16.

Is there any way to circumvent the automatic “background” login?

The MacBook Pro 16" is an M1 machine running macOS 13.6 Ventura.