Both were Trademarked by Liberty Import Export Company out of Quebec and appeared to have been made in Japan, Taiwan and a few others.
Levco skillets were trademarked in 1965. Typically came in 4 notch, but we have seen them with 3 notches. The handle style is very Canadian. We see skillets that are unmarked floating around, it’s safe to assume the pattern either has been copied or the patterns were passed around.
CASRON was trademarked in 1979. These are amazing chef skillets and take season really well.
Levcoware was trademarked in 1973. Edit TM initially showed 1988.
https://www.ic.gc.ca/app/opic-cipo/trdmrks/srch/viewTrademark?id=0357915&lang=eng&tab=reg&posNum=1&search=%7B%22selectField1%22%3A%22all%22%2C%22textField1%22%3A%22levcoware%22%2C%22category%22%3A%22%22%2C%22type%22%3A%22%22%2C%22status%22%3A%22%22%2C%22viennaField%22%3A%5B%5D%2C%22searchDates%22%3A%5B%5D%2C%22selectMaxDoc%22%3A%22500%22%2C%22language%22%3A%22eng%22%7D&length=25&start=0