Ascalonian alphabet

In Diessa Lowlands, halfway between Nolani Academy and the Ascalonian Foothills exit there's an old map of Tyria hanging from a post.

The map is written in old ascalonian runes. A closer look reveals that some of these runes are used to represent more than one letter. For example T and C use the same rune; A and V also share the same rune; the same happens with U and L; and again with E,F and H.

And yet the canonical ascalonian alphabet matches a single rune per letter so everything can be univocally translatable:

Line 1: ABCDEFGHIJKLM.
Line 2: NOPQRSTUVWXYZ.

There are two possibilities: either the map is written in an alphabet older than the canonical one or it was written by an apprentice scribe, which given the importance associated with such a task, seems to be the least probable possibility.