The team also placed defensive lineman Cap Capi on the non-football injury list Tuesday, three days before training camp.
Marks tore a knee ligament in last season's finale, but is on pace to return during camp.
Sample, a fourth-round draft pick in May, broke his forearm during organized team activities in June and had surgery the following day. He is expected to miss at least the first two weeks of camp.
Both players count against Jacksonville's 90-man roster and are eligible to be activated at any time. If they remain on the PUP list after final roster cuts, they must sit out the first six games of the regular season.
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