How to allow a client to use SAAS without violating the NDA?

Question

Copyright

A couple of years ago, I developed a specific web application for one client (hereinafter referred to as the "old client") for interacting with one large Internet portal. An NDA non-disclosure agreement has been entered into. Now I was contacted by another client (hereinafter referred to as the "new client") who wants the same solution (he does not know about the old client and does not know what a solution I have already done before), but in the form of a SAAS service so that the new client does not spend money on infrastructure , and I have free capacity. Those. he will not receive the source codes, only access to the web application through authorization through the login password that I will give him. In the web application, no personal data of the old client (his company) will be reflected, it will be hosted on my infrastructure and the databases are different.
https://yadi.sk/d/HRUXg77ML8W8gA?w=1

Will it be a violation of the agreement if I provide a service (subscription to SAAS - service) to the client who contacted me based on software that I developed a couple of years ago for another client? With old clients, apart from a non-disclosure agreement, I had neither an agreement nor an act.

Answer 1

And what does the NDA have to do with it, the question is who owns the rights to the code.