Bug when ranking up champion with 3 items with champion from carousal

Hi all,

Had a Rank 2 Rengar on the field, a Rank 2 Rengar on the line-up, and 2 x Rank 1 Rengar on the line-up also. Rank 2 Rengar had 3 full items already. Got a Rank 1 Rengar from Carousal which had a large rod.

After combing to Rank 3 Rengar, the large rod replaced one of the full items and pushed it out... Is this normal?

Thanks