There are multiple different interpretations of "copy" that systems use, and which one is correct will depend on the expectations of your users.
Option 1: Copy as part of a copy/paste pair of actions. The user is expecting to paste the copied form somewhere after they take the copy action. Traditionally, most systems do not offer any visual feedback that a copy has happened (except for maybe flashing the Edit menu if you have one).
Option 2: Copy as a single action for duplication. The user is expecting to see a second copy of the original form appear next to the original or somewhere else contextually relevant. This is often called "Duplicate" to make it distinct from option 1, but if it is the only Copy action available, users won't be too surprised this is what it does, especially if they get immediate feedback (which option 1 lacks).
Option 3: Copy as part of creating a new document. When creating a new form, the system may allow users to start with a copy of one that already exists rather than starting from scratch. Their expectations are probably around making revisions as quickly and easily as possible, so you should accommodate that.
Doing some usability tests with a few of your actual users should be enough to determine what their needs are around copying, and which option their mental model is expecting. Or your system could support all three types of copying (with clear labels) and then you can meet user expectations no matter what they are.
Additional note: As long as your system allows unwanted forms to be deleted, you probably don't need a prompt confirming the copy action, regardless of what it actually does. Accidental clicks are not that common and are less dangerous than a user that has been trained to accept any "Are you sure?" prompts without reading them.