merge.xts() does not currently honor check.names = FALSE. This is documented behavior, but it would be nice to have support.
x <- xts::.xts(1:3, 1:3, dimnames = list(NULL, "42"))
y <- xts::.xts(1:3, 1:3, dimnames = list(NULL, "21"))
merge(x, y) # leading "X" added
merge(x, y, check.names = TRUE) # same
merge(x, y, check.names = FALSE) # should have numeric column names
merge.xts()
does not currently honorcheck.names = FALSE
. This is documented behavior, but it would be nice to have support.