This comment only applies to DO students:
If you apply to MD internship and MD residency then you can coordinate the lists as described above.
If you apply to DO internship and DO residency then you can coordinate the lists as described above.
If you apply to DO internship and MD residency then you can NOT coordinate the lists as there are two separate matches. If you match into a DO internship you will be removed from any 4 yr MD residency programs. The other option would be to apply to DO internships and MD residency, not rank internship and wait for the MD match. If you match to a 4 yr program, you're done. If you match to a 3 yr program, you scramble into internship as there are typically many unmatched DO internships. You will potentially lose some control over where you do internship but I know people that are doing/have done it because they applied to multiple 4 yr programs but don't want to do a MD intern year.