That is true. There are some situations where this wouldn't work well but replacing thi:

SET @Master_Surname = LEFT(@Master_mkNormalisedName, CHARINDEX(',',@Master_mkNormalisedName)-1)

SET @Master_Forename = LEFT(SUBSTRING(@Master_mkNormalisedName, CHARINDEX(',',@Master_mkNormalisedName)+1,

LEN(@Master_mkNormalisedName)), CHARINDEX(',',SUBSTRING(@Master_mkNormalisedName,

CHARINDEX(',',@Master_mkNormalisedName)+1,LEN(@Master_mkNormalisedName)))-1)

SET @Master_MiddleName = REVERSE(LEFT(REVERSE(@Master_mkNormalisedName), CHARINDEX(',',REVERSE(@Master_mkNormalisedName))-1))

-- get the normalised name parts and the phonetic name parts for the duplicate record

SET @Duplicate_Surname = LEFT(@Duplicate_mkNormalisedName, CHARINDEX(',',@Duplicate_mkNormalisedName)-1)

SET @Duplicate_Forename = LEFT(SUBSTRING(@Duplicate_mkNormalisedName, CHARINDEX(',',@Duplicate_mkNormalisedName)+1,

LEN(@Duplicate_mkNormalisedName)), CHARINDEX(',',SUBSTRING(@Duplicate_mkNormalisedName,

CHARINDEX(',',@Duplicate_mkNormalisedName)+1,LEN(@Duplicate_mkNormalisedName)))-1)

SET @Duplicate_MiddleName = REVERSE(LEFT(REVERSE(@Duplicate_mkNormalisedName), CHARINDEX(',',REVERSE(@Duplicate_mkNormalisedName))-1))

With :

-- get the normalised name parts and the phonetic name parts for the master record

SELECT @Master_Surname = CASE ItemNumber WHEN 1 THEN Item ELSE @Master_Surname END

,@Master_Forename = CASE ItemNumber WHEN 2 THEN Item ELSE @Master_Forename END

,@Master_MiddleName = CASE ItemNumber WHEN 3 THEN Item ELSE @Master_MiddleName END

FROM dbo.DelimitedSplit8K(@Master_mkNormalisedName, ',')

-- get the normalised name parts and the phonetic name parts for the duplicate record

SELECT @Duplicate_Surname = CASE ItemNumber WHEN 1 THEN Item ELSE @Duplicate_Surname END

,@Duplicate_Forename = CASE ItemNumber WHEN 2 THEN Item ELSE @Duplicate_Forename END

,@Duplicate_MiddleName = CASE ItemNumber WHEN 3 THEN Item ELSE @Duplicate_MiddleName END

FROM dbo.DelimitedSplit8K(@Duplicate_mkNormalisedName, ',')

Is so much better!