List newform.aspx opens a different form in sharepoint 2013

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forms

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SharePoint2013

I hope someone could help my case:

We have a 2010 SP Server which was migrated to 2013 recently, and my assignment is to create custom List with Application page which invokes Web Part.
Our secured environment prohibits use of SP Designer, and functions only as .wsp deployment.

In the solution we have many projects, so I was able to find a similar project and copy it and work from this one (modifying every reference and names of display forms and so on), BUT at the END, when I deploy the project and open NewForm, it opens the old Web Part of the copied project. And I looked every inch of the code and could find the reference why id does this. Had someone experienced this?

Help would be appreciated, since I have a deadline to catch, and just spent 1 week doing just that.

I could provide the code but would need pointer what part of the code to examine.

Thank you so much

What I have tried:

Tried to add Application Page separately, but it didn't work. Tried creating new project (without copying old one) but it didn't work.