Overlapping of lwd and doj

I have worked with Company A from 20th May, 2015 to 30th Nov,2018 for his client ( Company B) on contract basis on payroll of company A. Latter I was taken as full time employee on payroll of Company B on 3rd Dec'2018 (it was conversion process from company A to company B) But during this conversion process HR team of company B shared may last woking them as contract basis with with company A as same as my DOJ with company B and when i received my experience letter from company A it was mention as 3rd Dec'18 as my LWD with and its same as my DOJ with company B. All in one it was company B HR team fault who shared wrong LWD to company A and they updated same in EPFO latter the experience latter from company A. Also it was accepted by company B with same DOJ joining i.e. 3rd Dec. When i contacted HR regarding same they said its ok as it just conversion process it will not have any issue But now when I am moving outside company B to new organization they are say this is dual employment case for that 1day.