Contrary to your belief...

The question on 'if denim can be worn with denim' is one people try to avoid asking because they think its impossible...well,I used to think any one who tried it would look tacky and funny till I saw D&G spring collection 2010 and the models were rocking all denim and I was loving it..
It is not impossible to rock the denim on denim ish..all you have to do is know how to do it right so you avoid looking like someone from the 90s.

 You could pair two different washes..a dark with a light shade of the same colour..that way you can work it well without looking tacky..

Or you can do it like my girl Riri and wear two different colours..this is the easiest and safest way to wear denim on denim..also black on blue is also a nice combination..