Can repeated call-signs be present in one day?
It is no problem to have the same call sign on the same day. As long as the same call sign is not uses at the same time there is no problem. 

For VFR flights, the same call sign can even be used at the same time as long as it is not in the same airspace. 

Many of the ADS-B duplicated call signs on a single are aircraft registrations coded in the transponder's aircraft ID field, typically from General Aviation flights