utf 8 - utf8_decode(): Same strings in UTF-8 returns different result (PHP)

I have two strings that look absolutely the same in UTF-8.

$string1 = "histórico";
$string2 = "histórico";
Copy code

but when I convert them to ISO-8859-1, (it doesn´t mind if I useutf8_decode,iconv ormb_convert_encoding) I get different output for them:

• The string1 converts to histoÌrico
• The string2 converts to histórico (that is, in fact what I expected for both strings)

Any idea?

Thanks in advance!