I have found it common for older things to be stamped with whatever they happened to have handy at the time.
Stamps could be interchanged or substituted.
L for 7
1 for I,
E+I next to it to make a B or 8.
8 for B
ect. ect.
Sometimes if they didn't have the right letter, they would throw in a letter that might make sense to someone that couldn't read that well.
Point being, that could be a 7 or an L.