Hey ,
Thank you for reporting that ctrl+z duplicates components that can’t be deleted in UE4 Version 4.7. I have tested this in 4.7.6 in the viewport as well as a blueprint and I was unable to replicate this. I went to Version 4.8.0 and tried to replicate it the same way and was unable to.
Where exactly are you adding the camera, in a blueprint? Please provide your full reproduction steps, and also see if you’re able to replicate this in 4.8.0.
I look forward to hearing back from you, thanks! 