Strange behavior when updating primary address

Hi Support Team,

I am facing strange issue whenever I am updating the primary address under accounts. Come to issue have taken S_PARTY,S_ORG_EXT,S_ADDR_ORG tables user keys, Primary address column(S_ORG_EXT) as well. I had chosen EIM_ACCOUNT for import process because it is having the Explicit primary mapping column. Whenever I start the update process it was updating the IF_ROW_STAT_VALUE=”DulicateRecordExists”.

Then I tried to update one unnecessary column (COMMENTS) along with Primary address. Then the import process completed successfully with IF_ROW_STAT_VALUE=”IMPORTED”. So what I want to ask you is why this strange behavior getting I am. Please could you explain me?