I don't know if you're asking if you need to do both WAEC & NECO. If that's your question, my answer is 'I don't think so'. It says on WES website "Final Secondary Examination results (e.g WASSCE)". That means WAEC.
If you don't have your WAEC result, you can try using your NECO. But I'll suggest that you not bother with NECO & just use WAEC.
If you don't have your WAEC result, you can try using your NECO. But I'll suggest that you not bother with NECO & just use WAEC.