It is one of those pointless apps, that provide low functionality but lead to the severe computer and privacy problems. It was developed to detect and remove duplicate photos and pictures. Similar Photo Cleaner is ad-supported application for Mac. To stop this and remove the reason for such errors, please, use instructions on this page. Here is the screenshot of such a pop-up message. Report malware to apple to protect other users. This file was downloaded on an unknown date.
'nspcuninstall' will damage your computer. In particular, the following messages are shown: After updating macOS to latest version (Catalina) users started receiving system errors related to files and processes of Similar Photo Cleaner: nspchlpr and nspcuninstall.