Are you sure of that? I'm only fairly new to Perl so I could be interpreting this wrongly, but in the Camel book (which I've been reading) it says:

"...But the ordering of the alternatives only matters at a given position. The outer loop of the Engine does left-to-right matching, so the following always matches the first Sam:"

"'Sam I am,' said Samwise" =~ /(Samwise|Sam)/;   # $1 eq "Sam"
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which suggests to me that the match earliest in the text will be found. If that isn't the case it's going to make my life a whole lot more difficult...:P