Sources said that the "inadvertent error" happened in one of the late evening bulletins yesterday when Doordarshan News carried Singh's visual instead Modi before introducing news-stories related to the Prime Minister's US visit.
Sources said the same visual was aired in some of other time slots as well.
When contacted, senior Doordarshan officials said the matter is being looked into.
A senior official said Doordarshan News had put into place a monitoring mechanism which immediately identifies if any error has occurred.
Recently, a newsreader on Doordarshan had mistaken 'Xi' in visiting Chinese President Xi Jinping's name for Roman numeral 'eleven' and pronounced it thus.
In another incident, DD News officials had set up an internal committee after one of its correspondents while reporting on Kashmir floods reportedly used the words 'Islamabad' for 'Anantnag' and 'Sulaiman' hill for Shankaracharya hill.