After entering my stimulus payment it read that i should have gotten more . However that is because i am claiming both my children this year instead of one. How do i refuse the additional stimulus pay

I am in the same boat.  My sons father claimed him in 2019 and 2018.  I am claiming him this year and its trying to give me the credit when I know I should get it.

Under the current guidelines for the Recovery Rebate the calculations you describe are correct.  The Recovery Rebate Credit is based solely on the tax year 2020 return information.  If someone else claimed your dependents and received a stimulus payment in rounds one and/or two based on prior year returns, that was correct for those payments.  You are filing for the tax year 2020 Recovery Rebate Credit.  

Here is a link with more information on the Recovery Rebate.

As for my daughter, her father claims her for the odd number years (court order) and I claim even.  He claimed her on his 2019 taxes, however he did not receive a stimulus check for her neither the 1st or 2nd time and neither did I.  Is there a way to recover that or am I missing something?  I just don't want to claim my son who already been claimed for stimulus and would to collect my daughters if possible. Or maybe they are its is giving me my daughters amounts versus my sons.

I thought the s2nd round of stimulus was based on 2019 taxes if they were filed and the 1st was based off of 2018 or 2019 if filed.... ?? 

You are correct on all statements.  Stimulus payments received for a child in rounds one and/or two are based on prior year return information. 

The Recovery Rebate Credit is based on tax year 2020 returns.  So if you claim a child under age 17 on your 2020 return that child would be eligible for the Recovery Rebate Credit. 

You will total your stimulus payments received and if that total is below what your 2020 tax return says you should get, a credit will be added to your tax return. 

If the total received is at or above what your 2020 return says you should receive, then no credit will be added.   

So despite only claiming 1 child on previous tax years   i am still due this additional payment?  I would hate to have to owe it back or be audited because the payment  for round 1 and 2 were given to to their father since he claimed 1 child last year. 

Yes, you are correct.  You should file your return for tax year 2020 based on your information for that tax year.  You should not be filing based on what someone else may or may not have received.