Google is Paying with QS ...?
Alternatively, you could have different destination URL's set at the KW level which would affect QS.
To be honest with you, I haven't done this ever (adding same keyword/same match type) within a single ad group
You should also understand that till the time your keywords doesn't accrue some minimum impressions, the Quality Score assigned is not actually your account specific, but is based on how other advertisers have used that in the past.
I would suggest you not to follow such practices actually where duplicate keywords are added inside the account because that's against the best practices of AdWords optimization.
It's better if you can add different variation of keywords, use tightly theme based ad groups and optimize your account accordingly.