annotation rolls/patents

Hello I am hoping that readers will have the answers to the following questions. I hope that the posting of multiple questions is acceptable. Why are a number of sailors registered under another sailor's patent? Could there be a connection between the 2 sailors or was it simply due to blank space availability? Why is there no sign on/sign off information for a number of sailors? Didn't all sailors have to sign on/sign off? If a person was registered for possible military duties, was that person allowed to leave the country prior to the expiration date? My grandfather was registered in May 1906 and it expired in March 1907. Was he legally able to leave the country during that time period, without facing a penalty if he returned to Norway? I am attempting to determine when he relocated from Norway. Thank You