<p>The colleges would surely know if someone applied early to BOTH colleges SCEA, which is against the SCEA rules at each place. We know from anecdotes here on CC that every year there are students who signal their first choice (by applying either ED or SCEA to the Ivy of their choice) who get rejected by their first choice (whichever college it is) but then get admitted by another college, sometimes a "better" or more desirable college, in the regular admission round. I'm sure that last year there were both early Yale applicants who were rejected by Yale but then admitted by Harvard in the regular round, and the other way around. </p>
<p>In short, colleges don't hold it against you that you apply to more than one college, nor do they hold it against you that you do the smart thing and apply SOMEWHERE in the early round. You decide which early round opportunity to use. I agree with Byerly, having consulted the same sources that he cites, that every college (with the possible exception of MIT) has a higher base acceptance rate for its early applicants than for its regular round applicants. So if you like one particular college, apply to it early to maximize your chances. If you have other colleges that look like good choices to you, apply to those in accordance with the rules of the early round college. (For example, most of the SCEA colleges allow "rolling" applications to a state university at any time, so if your state university is a satisfactory "safety" school, one you would like to attend, apply there as soon as you can put your paperwork together.) </p>
<p>Don't worry about psyching out admission officers too much. They themselves acknowledge that two "equally" selective colleges can treat "comparable" applicants with inconsistent results. Just be sure to APPLY to the colleges you would really like to attend--you can't get in if you don't apply.</p>