tractorwoner,
What I meant was that sometimes an image of Olympic is substituted for an image of Titanic. So when we think we are looking at Titanic being built we may be looking at Olympic.
If you take a look at a lot of pictures which say 'Titanic in dry dock' or something it may not be Titanic at all.
Neither the ships or any parts of them (other than a propellor), i believe, were swapped. If you have any pictures of Titanic in dry dock or if you see some on the internet compare them to Titanic at sail and you may see slight differences. This is not because any parts were altered or swapped but simply because they are probably not Titanic.

sas