We assign one customer personal discount PED and shipping exempt SHE

When he puts something in his cart it assigns his discount but it also allows the product discount, so he is 'double dipping'.

His personal discount is 20% so on some products he is getting a 40% discount!

I can''t see anything in includes that would affect this.

Help please!

Please ignore this- we can't replicate what the customer says happens when we try it