Brighton striker Dickenson was ineligible for the 2-1 FA Cup defeat by npower League One leaders Tranmere while MK Dons midfielder O'Shea was cup-tied for the second-round clash at Prenton Park.
The Spireites came through the game against Rovers without sustaining any injury problems.
As well as Dickenson and O'Shea, manager Paul Cook also has the likes of midfielder Mark Randall and strikers Jack Lester and Scott Boden pushing for recalls to the starting line up.
Chesterfield head to Vale Park in good form having won their last three league matches.
Cook also has a victory over Vale already this season, guiding his former club Accrington to a 2-0 home success back in August.
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