The MG Vaishali was a different train. In the late 1970's, it was running from Siliguri to Agra Fort. After the gauge conversion of the Lucknow-Gorakhpur route, it was short-terminated.
The present Vaishali was introduced as 153/154 Delhi - Muzaffarpur Jayanti Janata express. It used to run via Kanpur-Allahabad-Varanai-Mughalsarai-Patna-Barauni-Samastipur. After the gauge conversion of the Lucknow-Gorakhpur-Muzaffarpur route, it was rerouted via GKP and was renamed as Vaishali express.