kim, knowing the diameter of the oral disc in relation to the average length and longest length of it's tentacles will help with it's i.d. i asked for the measurements of both anemones for comparison because we know your avatar is H. malu.
have you noticed any differences between their column's? the underside of H. malu's oral disc is said to be colored a darker violet brown then the rest of the column because of the presents of zooxanthellae.
fwiw,
i'm still not sure of my current sebae's i.d. which has a ø of 6" when scrunched to 8"ø when spread out with tentacles that max out at 2"-2.25", most average 1.5". some days the tentacles are slender and longer and other times are shorter and stout tapering to a point more like those of H. malu. it was the size of a small sea scallop from the sea food store a year ago when i got it. my last sebae was clearly H. crispa with a 15" diameter/3"-4"slender tentacles when i sold it however when it was new, smaller and coloring up i was thinking H. malu.