Importing Stage 2 make it double stage 2

we use DHIS2 2.31.5
After Importing Stage 2 with DE values in App management - excel import, we know that if stage 2 already opened blanked manually before, importing notify us coz its not repeatable so no double stage happened. But! if stage 2 already opened with value manually, importing continue normally and double stage 2 so we found 2 stage 2 and every one with value (1 manually and the other imported)
how can we import stage 2 and always skip opened stage 2 with/without values?