I suspect an unusual request, but a respondent needs to allocate 100 points to certain attributes, so I was going to use a constant sum or a matrix constant sum. However, in one version of the question, respondents aren’t allowed to give the same answer more than once ie.they can’t answer 50,50, or,they can’t answer 25,25,50, or,they can’t answer 10,10,10,70 etc.etc. And in another version of the question, they aren’t allowed to give the same answer more than twice i.e.they CAN answer 50,50, or, 25,25,50 etc., but they can’t answer 10,10,10,70 or,they can’t answer 25,25,25,25 etc. Is this possible?

Yes, it is possible. I recommend using a hidden question that you update with JS and use in a custom validation condition.

Avoid duplicate answers in a constant sum/ matrix constant sum

Avoid duplicate answers in a constant sum/ matrix constant sum | Experience Community