Problem if the Hire date is altered on hiring an employee using Position Number and Contract Data

When hiring a new employee and if the Next Contract Number field on the Job Information Page in Job Data is clicked, and if Hire Date is changed prior to saving, the system issues the error "Date being added conflicts with existing data" when there is actually no conflicting data in the system.

On Changing Hire date of an employee the position entry date does not get updated in PS_JOB record and I have previously posted about this. Click here to access this post - Issue with Position Entry Date on Hire Date changes

I could not find out myself why this issue. However found valuable information in Customer Connection as below.

Applies to:
PeopleSoft Enterprise HRMS Human Resources - Version: 9 - Release: 9
Information in this document applies to any platform.

Symptoms:
Issue Clarification (IC) :
When a using hiring a new employee has created the Hire Row and clicked the Next Contract Number field on the Job Information Page in Job Data, if they subsequently change Hire Date prior to saving the Record, when they click the Save button the system issues the error "Date being added conflicts with existing data"

Cause:
CAUSE DETERMINATION (CD) :
This issue has been caused by incorrect use of the functionality, as per the incident 1851071000 assessment by development.

CAUSE JUSTIFICATION (CJ) :
Existing Incidents ICE 1851071000 - Problem when hiring an employee using Position Number and Contract Data if the Hire date is altered from the defaulting Effective Date.

Details:
When hiring a new employee onto the system using a position, and the New Contract Number push button on the Job Information, page completing the mandatory data, then returning to the Work Location page to update the Hire date causes the system to issue the following error: "Data being added conflicts with existing date (18,2)"

Development have assessed the functions being used in this issue and have supported their decision that this is WAD.

1. It is expected that there is a general flow for the business process. All the defaulting/validations happen based on this assumption. In this case the effective date would already be present before creating a Job record. Why is it that the user fills in all the data and just before saving, changes the effective date? Is it a user error? If so this should be an exception rather than a norm. The user should choose the right effective date to key in and transaction gets processed correctly. 
2. When the error occurs the transaction is not saved, so there is no question of Hire date not getting populated as claimed in the Customer Impact Statement doc

Solution:

1. Instead of the User updating the Effective date after making all the other necessary entries to the Job Data Record and then updating the date, the date should be changed when the user first accesses the page, as per the normal data entry functions advised by Oracle/Peoplesoft.
2. In case the wrong effective date is keyed in and saved, start with creating a new transaction. The user just needs to create a new Job record as the Person record is already created.

References:
BUG:1851071000 - PROBLEM WHEN HIRING AN EMPLOYEE USING POSITION NUMBER AND CONTRACT DATA IF THE HIRE DATE IS ALTERED FROM THE DEFAULTING EFFECTIVE DATE