[Dx4win] County Line Contacts

[ShelbyK4WW]

I encountered a situation, in last weekend FLQP, and will probably
encounter it again, this weekend in 7QPINNE QSO parties.
Using N1MM+, which logs, creates ADIF, and Cabrillo fine. My situation
arose when importing the ADIF file into DX4WIN, an error message indicating
the second contact, with a county line station, was a duplicate, and the
import stopped. N1MM+ indicates a 2-3 second interval, in the ADIF file. My
work around was to manually edit the ADIF file, changing the time of the
second contact by one (1) minute. I also encountered a similar error, when
uploading to eQSL. What is the required time difference between stations
with same call sign, to not be considered a duplicate contact?
Thanks

73, Shelby - K4WW
As I don't have an iPad nor iPhone, sent from my PC