lambda x,a,b,c,d:(x+(100*((a==b)+(a==c)+(a==d)+(b==c)+(b==d)+(c==d))or .1)+177*(a==b==c==d))/100
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This version outputs excess decimals on zeros (e.g. 0.95 instead of just 0). If that is incorrect, an alternate solution for 98 bytes is:
lambda x,a,b,c,d:(x+(100*(100*sum((a==b)+(,a==c)+(,a==d)+(,b==c)+(,b==d)+(,c==d)))or 10)+177*(a==b==c==d))/100
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