RDB the Elder:
in Sh'mini, tzuveiti comes before tzuveiti <
Personally, I find it easy to remember: the first time, MRAH is passing on a Divine commandment (just as we often see "vaydabeir H' el...," here we see "vaydabeir Moshe el..."), so he was "tzuveisi" (viz. "eis asher y'tzuveh" at the end of P'Ki Sisa); the second time, he's upset with someone apparently not following what he had commanded b'sheim H', hence they should proceed "ka'asher tziveisi."
On the subject of simanim and this time of year: anyone have "hu"/"hi" simanim for "nega'"/"tzara'as"?
All the best from
Michael Poppers * Elizabeth, NJ