The ReplacePhoto method replaces a photo with a different photo.
void ReplacePhoto( long originalId, long replacementId )
The photos identified by the originalId and replacementId parameters must be owned by the currently authenticated user.
When a photo is replaced, its identifier and its URL do not change. In addition, the photo retains its original title, caption, categories, keywords, and access control settings. On the other hand, the actual photo image, date taken, date uploaded, and rotation attribute are copied from the replacement photo.
The ReplacePhoto method does not affect the replacement photo in any way.