since 2003 海關 and 移民局 at the port-of-entry became one and the same: CBP (Custums and Boarder Patrol) and reorganized under just one DHS from formerly three: Justice, agriculture and Treasury.
移民局 is more suitable for the INS era, because USCIS is now only 1/2 to 1/3 of the INS(移民局) we used to know. USCIS is not related to officers at port-of-entry anymore.
Back to the question, by law, immigration officers should not let you in. Whether you will be able to return depends on your luck that the specific officer that will check your document overlooks.
移民局 is more suitable for the INS era, because USCIS is now only 1/2 to 1/3 of the INS(移民局) we used to know. USCIS is not related to officers at port-of-entry anymore.
Back to the question, by law, immigration officers should not let you in. Whether you will be able to return depends on your luck that the specific officer that will check your document overlooks.