In cell B1, use the formula =LOWER(A1) to convert the value of A1 to
all lower case. Copy that formula down thru B900. Then copy column B,
and Paste Special as Values onto column B, converting the formulas to
text. Highlight column B; search for " " (two spaces, but don't use
the quotes) and replace with " " (a single space, no quotes). Repeat
the search and replace until you get the "can't find anything to
replace" message.