I've got an ExpressionEngine database and I exported a couple of tables from it, then dropped those tables. When I try to re-import the tables in PHPMyAdmin, I get this error:

SQL query:

-- -- Database: `my_db` -- DELIMITER $$ -- -- Functions -- CREATE DEFINER=`my_username`@`%` FUNCTION `LEVENSHTEIN`(s1 VARCHAR(255), s2 VARCHAR(255)) RETURNS int(11) DETERMINISTIC BEGIN DECLARE s1_len, s2_len, i, j, c, c_temp, cost INT; DECLARE s1_char CHAR; DECLARE cv0, cv1 VARBINARY(256); SET s1_len = CHAR_LENGTH(s1), s2_len = CHAR_LENGTH(s2), cv1 = 0x00, j = 1, i = 1, c = 0; IF s1 = s2 THEN RETURN 0; ELSEIF s1_len = 0 THEN RETURN s2_len; ELSEIF s2_len = 0 THEN RETURN s1_len; ELSE WHILE j <= s2_len DO SET cv1 = CONCAT(cv1, UNHEX(HEX(j))), j = j + 1; END WHILE; WHILE i <= s1_len DO SET s1_char = SUBSTRING(s1, i, 1), c = i, cv0 = UNHEX(HEX(i)), j = 1; WHILE j <= s2_len DO SET c = c + 1; IF s1_char = SUBSTRING(s2, j, 1) THEN SET cost = 0; ELSE SET cost = 1; END IF; SET c_temp = CONV(HEX(SUBSTRING(cv1, j, 1)), 16, 10) + cost; IF c > c_temp THEN SET c = [...]

MySQL said: Documentation

#1304 - FUNCTION LEVENSHTEIN already exists 

I get this error even if I drop all tables from the DB and try to import anything. The only way I can get the error to go away is to totally delete the database and re-create it.

What's causing that error and how can I stop it from happening?