Highlight duplicate numbers

Hi, i am new users and not too good with excel. I need to do this...

How i can highlight the row if the number is the same but ignoring the -ve or +ve. eg as per below. You may see the number in row 1 and 3 is the same but the row 3 has -ve sign. Appreciates your help



A B
123 a
123 b
-123 a

Hei thanks so much for your simple answer but really help me a lot. Need further helps, how should i combine the ABS function in this formula =if(COUNTIF($C$6:C6,C6)>1,"Duplicate","").