if an arg contains a %1 pattern that pattern will not be copied to the target string

I have this code

QString( "%1 foo %2" ).arg( Str1 ).arg( Str2 )

Str2 contains

"bar"

now - by chance - Str1 contains

"baz %1" 

I get as output

"baz bar foo %2", and not as I would expect

"baz %1 foo bar"

So it seems that the %1 of the Str1 value is used as pattern and that - as Str1 is processed, Str2 becomes the value for %1 and not for %2