When using the spreadsheet functions MATCH or VLOOKUP to search a table for an exact match, where sort order or type = 0, these functions only seem to look at the number of characters of the search criterion within the strings of the search array. For example search for "dev" will be considered an exact match to "develop", but this is clearly not an exact match. Search for exact match implies both strings must be the same length. Tested with regular expressions enabled and disabled and both give the same result. I checked using Excel 2010, which seems to give the expected result, "dev" does not match "develop".
Confirmed the same issue is also present in 5.1.3.2, 32 bit version. Also in 5.0.6.3 x64.
Check your setting of Tools - Options - Calc - Calculate, section "General Calculations" "Search criteria = and <> must apply to whole cells". Likely it's off, set it on.
Thanks, It was off, never expected this to be a configurable option.