actually, that's not true. i was always under the same impression as you that schools in US don't seem to encourage or even allow second undergrad degrees, having read somewhere before that a first undergrad degree disqualifies you from applying for a second. however, due to a series of unfortunate events, i have discovered that it is not true at all.

source = me. i'm currently admitted back to my alma mater for a second degree in CSC and will be returning in fall this year.