I'm not a friend of the "another new sub-SPOJ contest". It would split the one and only SPOJ into parts and take something away from its "spirit".
I would be prefer not to change too much. Of course, it is unsatisfying as it is, but maybe there is not so much that can be done to generate a satisfying state.
Changing old classical problems into a kind of "published and thus worthless/pointless etc." problem is not fair for all those, that solved the problem either before
they were published or nevertheless completetly on their own. I do not believe that the main interest of all new problemsolvers is to find a published solution and get their points for submitting that. Of course, there are such "problemsolvers" (which in fact are not what the name says), and whenever one of those is detected, he/she should be banned.
What could be done in my opinion without too much effort is:
1. If problemsolvers have a link on there user side that leads directly to published solutions, explain to them the effect of that action and ask them friendly to remove that link. I they do not react, ask them again (not so friendly), set a time limit and ban that user after time is over.
2. If problemsolvers do not have a link on the user side, but a blog/site or whatever with published solutions that is connected to the user name, explain to them the effect of that action and ask them ... see above.
Maybe in some cases it would help to offer those publishing users an alternative, as they seem to like telling the world about their solved problems.
instead of publishing the solution, they could explain the/one idea that is behind the problem and an approach for solving it. Even this is a kind of spoiling, but it is by far better than a complete AC code, that has only to be copied and pasted to get a green SPOJ-light. Anyway a link even to those publications shouldn't be allowed on the user page.
My experience: I tried item 1 of my above suggestions upto the "ask friendly" part. Result was, that this user (with link to published solutions on the user page) apologized and removed that link immediately. He was not aware of what was done with his publications.