You have made an error in the year of passing. With regards to DSSsB PRT forms, like any online application, mistakes would be made at the initial stages. Given the huge number of applicants, it is impossible to rectify the mistakes of many applicants at this stage. Hence candidates are discouraged from submitting multiple forms.
If the error is related to cut off marks, caste etc, then you need to follow up with concern.
You can wait, prepare for the exams, Once you write the exams and you are selected for the interview, you can contact the authorities or explain to them during the document verification stage with the valid originals of the 12th class.
If you are concerend and unable to focus on your preparation. Draft a letter to the controller of exams, attach a copy of the form, a copy of the valid 12th pass card and clearly explain the mistake and keep the reciept of postage by Speed Post or Registered Post. You can use this when it comes to document verification stage.
Controller of Exam,
DSSSB, Delhi Subordinate Services Selection Board
Institutional Area,Near Railway Reservation Center
Delhi - 110092, Telephone: 011-22370309