This is the result I get:
> dput(head(full_data_1))
structure(list(id = c("123A", "123A", "123A", "123A", "123A",
"123A"), Date = structure(c(NA_real_, NA_real_, NA_real_, NA_real_,
NA_real_, NA_real_), class = "Date"), usage = c(10, 12, 40, 20,
11, 20), treatment = c(0, 0, 0, 0, 0, 0), Gender = structure(c(2L,
2L, 2L, 2L, 2L, 2L), .Label = c("Female", "Male"), class = "factor")), row.names = c(NA,
6L), class = "data.frame")