E-2 Visa in passport?

My mother holds an E-2 business visa and was told at customs last week that she needs to have a "ten year visa" stamp or sticker in her passport. The E-2 is only a two year (renewable) visa so does anyone know what the immigration official meant? Apparently, its not the I-94 I thought we need to replace :S

No idea, E-2 is quite rare so maybe he made a mistake. As you say, it is a two-year visa. B-2 can be ten years, but that doesn't apply to Canadians (as nearly all non-immigrant categories except E and K don't require a visa). I'm assuming he didn't know what the maximum validity for E-2 is.