How to prevent duplicate entries in two columns with formulas?

Friends,
Although I have been a member for a while I rarely post. I usually just look for answers. But! I am stumped on this one! I have two columns; A:A has text and B:B has a numeric value. For each text there can only be one associated numeric value. There can however be duplicate text in column A:A, just cannot allow duplicate numeric value in column B:B. Can I prevent this with formulas or Data Validation? I THOUGHT I was savvy with excel. I stand corrected!

Hi Cody,
Find attached sheet. Is this sort of what you want? If duplicate number is entered in column B it will give an alert saying "duplicate"

Wow, thank you both for the help. Very quick! I have one more question. What if I have two columns with text and two with numeric value and I want to prevent duplicates as if the four columns were a group. IE both text columns were one designation and the numeric columns were another?

I have attached an example in the book1 that moppyau sent. Thanks very much!

Ok, I think I have attached a more clear picture of what I need. Hopefully! What are your thoughts?

Hi Cody. Looking at your example I don't think my method will work. I used data validation which won't let you enter the same number in the one column twice, it looks like you need to be able to have say 2 hats & 2 shoes, is that correct? I'll keep trying.

That's correct, I need same commodities with different push orders. To keep FIFO in order.

Ben, this worked perfectly, they were in fact linked! Sumproduct seems to be the most difficult for me to learn. Thank you very much!

Your very clever Ben.

please provide the example excel sheet

Originally Posted by benishiryo

still not sure i understood correctly. use the same instructions i mentioned but select E5:E15 instead. put in the custom formula:
=SUMPRODUCT(--($D$5:$D$15&$E$5:$E$15=D5&E5))+SUMPRODUCT(--($H$5:$H$15&$I$5:$I$15=D5&E5))=1

this links the table across too. that means the 2nd table cannot have Shoes with 1, since it already appeared. is that right? if it's not linked, then just:
=SUMPRODUCT(--($D$5:$D$15&$E$5:$E$15=D5&E5))=1

then in the 2nd table, select I5:I15 & do the same. but formula as:
=SUMPRODUCT(--($D$5:$D$15&$E$5:$E$15=H5&I5))+SUMPRODUCT(--($H$5:$H$15&$I$5:$I$15=H5&I5))=1

again, if it's not linked, then just:
=SUMPRODUCT(--($H$5:$H$15&$I$5:$I$15=H5&I5))=1

please provide the example excel sheet for the above...