Yes, there is. In fact SPI (sockpuppet investigations) is known as one of the hardest "departments". You'd need pretty suspicious behavioral evidence before filing one for good reasons. Clerks need to sort through all the requests and see which ones deserve the actual IP-inspectors (CheckUsers) to check if the users seem to be the same (or an open proxy. Don't worry, the IP address retention period is only 90 days). Also, cases to check if an IP address is the same as an established user will never be CheckUser'd cuz that would be exposing the IP address though it won't go unpunished and will be judged purely on behavioral evidence.
Sockmasters who span ridiculously long amounts of time are documented at WP:LTA (long-term abuse). However, ones that inspire copycats (like some WillyOnWheels who move-vandalized tons of pages) have their documentation deleted as part of a policy called Deny Recognition (to the trolls).