add a check for non-unique decorator names (#828)

The same as in tmc

insightsengineering/teal.modules.clinical@b048f37
do not allow decorators with duplicated names

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Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

R/utils.R

@@ -350,6 +350,14 @@ check_decorators <- function(x, names = NULL) { # nolint: object_name.
     check_message <- if (isTRUE(check_message)) {
       out_message <- checkmate::check_names(names(x), subset.of = c("default", names))
       # see https://github.com/insightsengineering/teal.logger/issues/101
+      if (length(names(x)) != length(unique(names(x)))) {
+        unique_message <- "Non-unique names in decorators"
+        if (isTRUE(out_message)) {
+          out_message <- unique_message
+        } else {
+          out_message <- paste0(out_message, ". Also, ", tolower(unique_message))
+        }
+      }
       if (isTRUE(out_message)) {
         out_message
       } else {