Testimo is a PowerShell module that doesn't have Active Directory code. It's a bit more like a wrapper around multiple other modules. It integrates GPOZaurr, ADEssentials, PSSharedGoods, PSWriteHTML or PSEventViewer. All written by me, all are doing their part. ADEssentials contains a command used by Testimo to provide a graphical representation of it. By using Get-WinADDuplicateSPN without any parameters, you can quickly find duplicate SPN's.
You can also use All switch if you would like to see all SPN entries instead of just duplicates.
In Testimo, I wrap around it and assess how good or bad the given data is. The assessment, of course, is based on my judgment, and you can disagree. It's more of a guidance than anything else, so make sure you diagnose why this is rather than going through and fixing everything it tells you to improve. In Testimo, I also try to add descriptions and links that you may find helpful in figuring whether the test makes sense to your environment.