Considering this lot, which is going in next month's sporting and collector firearms auction at Rock Island.
https://www.rockislandauction.com/detail/1041/6864The older gun (top one in the picture) was produced in 2006, and is therefore a pre-Remington takeover built model and not an issue.
The bottom one is the worry. You can't date a Remington-built Marlin (Remlin) based on the serial number. There's a 2-letter stamp elsewhere on the gun which denotes year and month of production, and this stamp is impossible to make out in the photos provided. I've emailed them to get that info, but that usually takes a while. I'm not a patient person.
Rock Island is a great company, through which I've bought and sold dozens of guns, ranging from the new and unused to early 20th century war relics, so I expect them to be forthright, but figured I'd toss the question out here regardless. I'm no expert on Marlins, and one can't overdose on wisdom.