payroll duplicated

Hi. 

I came on board a company and started to update payrol inputs

I first established employees ytd to verify with gl ledger and discovered a pay had been duplicated: 

Has anyone experienced this? 

Its a nightmare. if yu delete the duplicated ( its possible in myob payroll) its essential to go on ird

site and manually delete the entry

My question us how is it possible 

to process the same emplyee

same date range ?? Surely the programme would put up a flag 

querying " chek duplicated data"

to ensure the validity? I would have thought it impossible to duble process identicle data for identicle employee