iFrame has broken a post – and it remains broken when the iFrame is removed

I added an (Amazon affiliate) iFrame to a post. the iFrame displayed fine, but now the post partly repeats at the bottom.

Here’s the post.

I removed the iFrame, but still the post is partly repeated at the bottom.

Can anyone help explain why? I’ve taken a look at the code and can’t imagine what the problem is. It doesn’t happen on any other page or post.