Check Duplicate same request

Users submit a lot of applications with different fields, the same processes are launched. How can I set up a check for duplicate applications for such processes?
For example, field 1 = field 2 in different processes.

@Evgeny you can configure a event listener in a start event of a process and you can query for existing process instance with variables in task Listener and throw a exception or return a required response for your process.

execution.getProcessEngineServices(). runtimeService()

Using runtimeService service you can query for existing process instance with variables

I thought about this option, but it does not suit me, because the fields of the object can change.
I assume that the fields must be stored in a separate entity.
Correct if I am mistaken.
How to do it in camunda (Apache Tomcat)?

Are you using camunda tomcat distribution and process application deployed in it? Deployment is based on single node or clustered node?

Camunda process engine service provides OR QUERY search filters, so you can compare multiple fields for the process instance.

Yes, I use Tomcat on one node.
Give an example of changes in completed processes of variable fields.
My fields could change not only in this process, but also in others.
Is this the right decision?

Could you please explain, what you mean by that?

In general, it is a good idea to prevent users from starting instances until at least a basic dataset has stabilized and there is a clear intent that the user will continue with the process instance.

The task is this:
a process is started in which the user fills in the data using a user task, the data is saved in variables in the process instance, the process ends.
Further, the business data of the fields changed by some other process, which were recorded in the first process. We have changed.
Then another process for creating the application starts, the user completes the task and I need to check the data for duplicates and not save the application in the database.
How to solve this business problem?

By application I mean a business entity in which data will be stored. For example, amount, date and more.