Duplicate Execution of Activity in Alterations

## Description
When migrating a workflow instance to the latest version (where a sub-process has been updated), a step inside the sub-process executes twice instead of once.

No error messages appear, but this leads to duplicate task execution and workflow inconsistency.

## Steps to Reproduce
1. Create two sub-processes `SP-1` and `SP-2`.

2. Create a main workflow using these two sub-processes.

3. Create a workflow instance of the main workflow.

4. Complete both steps in `SP-1` and finish that sub-process.

5. Complete the first step in `SP-2`.

6. Update `SP-2` by adding a new step in parallel with `Step-2`.

7. Migrate the current workflow instance to the latest version.

8. Since `Step-3` is not active, try to activate that step using **Schedule Activity**.

### Problem
- When the step is activated, its execution starts **twice**.

## Reproduce Rate
- **Every Time**
(This is specific to activity activation. If the same scenario is tested with sub-process activation, it works fine.)

## Expected Behavior
- Step 3 should be activated and executed only once to maintain integrity.

## Actual Behavior
- Step 3 is activated and executed **twice**.

## Environment
- **Elsa-Core**: Branch `develop/3.5.0`
- **Elsa-Studio**: Branch `develop/3.5.0`

@sfmskywalker
Could you please look into this issue?
If there are any quick workarounds or temporary fixes available, kindly suggest those as well.

Reproduce the scenario on the develop/3.5.0 branches using the listed SP-1, SP-2, and main-workflow steps, then trace the Schedule Activity path after migration. Done means Step-3 is activated and executed exactly once, while the equivalent sub-process activation scenario continues to work.

Written by the indexing model from the issue text.