Actually, I think your second step is wrong. You still have a one to many relation - page has many page_columns - but now a one to one relation between page_column and column. I'm sure that's wrong: 1:1 usually indicates the two tables are the same object, and you would amalgamate the tables.

I don't think there is anything wrong with the original 1:N design - are you sure you're not confusing the rule about M:N relations? Then you would have a new entity table (as you have) and two one-to-many relations to the original tables.

I know this isn't answering your question, and I always hate it when monks answer "Your question is wrong, here is the answer". But, I'm fairly sure you don't want the above design, and it not working in Class::DBI easily is a good indicator of that.