Mark, I think your answer might be here. It looks to me that the two marriages of Thomas in Shipley you found are the same Thomas Rhodes! He married twice, both wives having the name Ann. The clue is with the witness, Joseph Pierce.
To verify this you will need to find the burial of the first Ann and see if you can find a connection within the family with these witnesses. I've had a quick look on the Sussex Marriage Index but nothing is glaringly obvious

Shipley, West Sussex, Date: 29 May 1823:
Thomas RHODES
Ann LONGLEY, botp (B)
Witness wit. William BURSTOW, Joseph PEIRCE
Shipley, West Sussex, Date: 17 Jul 1825:
Thomas RHODES, widr
Ann JOHNSON, sp botp (B)
Witness wit. James & Mary BOTTEN, (Joseph PEIRCE, P. Clerk )
Jane