I've always heard that many of dook's programs are quite inflated, actually. Also, the perception that schools are more rigorous at private schools than large state schools seems pretty ignorant, elitist, and ridiculously pretentious.
In any case, adcomms have access to the average GPA of people applying from your UG, so they can see how inflated/deflated the grades are (and of course, how you compare). While a 3.85 from dook and a 3.95 from IU will probably be treated pretty similarly since they're always going to both be in the middle 50% (and usually above the school's 75%title), the likelihood of one getting in from dook is probably higher because they are probably a higher quality student (which would probably shine through in the rest of the application). Probably is the key of course. It's tough to give too strict of an answer.