AP.AP_PAYMENT_DISTRIBUTIONS_U1
This should tell you everything that you need to know. You are importing duplicate rows into the "AP" schema. Perhaps you should either import into a new instance and let the import create the apps users or you should import one schema at a time and create the new schema users ahead of time.

Code:
imp system/manager file=myexp.dmp fromuser=ap touser=ap_test ignore=y rows=y buffer=102400
imp system/manager file=myexp.dmp fromuser=gl touser=gl_test ignore=y rows=y buffer=102400
imp system/manager file=myexp.dmp fromuser=etc touser=etc_test ignore=y rows=y buffer=102400