This article explains how to restrict users from selecting the same values in two fields using Column Validation feature.
Steps to Restrict Users from Selecting the Same Values:
Step 1: Access Column Validation:
1. Click on KWIZ Apps in the ribbon to open the KWIZ Apps settings page for the list.

2. Select Column Validation

3. In the Column Validation settings, choose the field you wish the rule to apply to.
Step 2: Set Up the Rule.
- Validate Value: does not contain
- Insert Token: Click the "Insert token" button and choose from the list of columns
- Otherwise, show: The message that will be displayed when the same value is used

Results:

Repeat for any other validation