Vaishali Express - जितना सुंदर तुम्हारा नाम उतनी सुंदर तुम्हारी चाल - be my valentine - Rahul Vatsa

Why does this train use number series of WR and NWR i.e. 209 starting
whereas the Rsa partner Mathura -Howrah Chambal express has number of 121 series i.e. CR and WCR series
Interestingly it's Rake is of NCR
was this train previously running? If yes with which number ?

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