onChange client Scripts are executing twice on Date Variables when their value is cleared or changed as part of the script in Service Portal

1. Log in to an OOTB London instance (verified in demonightlylondon)
2. Open the record producer 'Create incident'
   • https://<instance-name>.service-now.com/nav_to.do?uri=sc_cat_item_producer.do?sys_id=3f1dd0320a0a0b99000a53f7604a2ef9
3. Create a Date variable, say 'start_date'
4. Create an onChange catalog client script on the above Date variable as follows:
   • Name: test alert
   • UI type: all
   • Type: onChange
   • Variable name: start_date
   • Script:

     function onChange(control, oldValue, newValue, isLoading) {
       if (isLoading || newValue == '') {
         return;
       }
       //Type appropriate comment here, and begin script below
       if(newValue) {
         alert("Called-oldvalue:"+oldValue+";newvalue="+newValue);
         g_form.clearValue('start_date');
       }
     }

5. Open the Record Producer from the Service Portal
   https://<instance-name>.service-now.com/sp?id=sc_cat_item&sys_id=3f1dd0320a0a0b99000a53f7604a2ef9
6. Select a date for the above Date variable

Expected behavior:
When you change the value of Date Variable 'start_date', the alert should show once.

Actual behavior:
When you change the value of Date Variable 'start_date', the alert shows twice.

Note: The issue is seen only on Date variables. If we repeat the same steps for a Single Line Text variable, the alert is shown only once.

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