I just spent 2 hours organizing a new profile for my 436, saved it, started a new profile to import the current state of my 436, tried to open my new profile again and it is the same as the 2nd profile I created!!!! WTF? Is Undo really hard to program these days?? What an antiquated POS.
If you read the radio into your new profile, it will replace the new profile with the settings or profile stored in the radio.
I have several profiles and just open one and write it to the radio before I read the radio.
I ran into the same problem as you when I brought my 436 home from work. Not thinking, I read it into Sentinel and my main 536 profile was overwritten by the profile and data from my 436!
In my case, I was able to simply create a 536 profile and then just read my 536 back into Sentinel and I was back in business.
Being as you can't have more than one copy of Sentinel installed, I ended up installing a copy on another machine that is used for just the 436 as I kept forgetting to open the correct profile before reading or writing the radio I was working with.
I don't find Sentinel to be a POS as you called it. It may need some small tweaks here and there but for the most part, it is very easy to use and does what I need very well.