Comparing data in two text fields

I have two text boxes which compares the value in one text box with other. Assume Text Box 1 has value as 1234 and Text Box 2 has value 12345,123,12346. Now I will be greying out the text box 1 by applying rule as If Text Box 2 contains Text Box 1 then do conditional formatting of greying out. In this scenario Textbox 2 doesn't contain the value of Text Box 1 how ever the condition turns out to be true and then greys out. Its takes 123 which is present in text box 2 and as it finds relative match with 123(neglecting 4) it is returning true.

Text Box 2 value is obtained by concatenating several text box values with commas. I want to perform exact match and grey out if it contains. Is there a way I can grey out the text box 1 by comparing the value in text box 2 before and after comma of each value in textbox.

Thanks