DISTINCT return same ID two times wrongly - sql

Question

This is my SQL query:
SELECT DISTINCT(ItemId), TCode, PartNumber,ModelNumber, ItemUOM
FROM #Results
This query returns:
ItemId TCode Source PartNumber ModelNumber ItemUOM
-----------------------------------------------------------------
1024 1000 NULL NULL EA
1024 1000 FLEX FLEX EA
#Result is a temp table I have used left join in that query
Why does SELECT DISTINCT return the same ItemID 1024 twice?
SELECT DISTCINT(I.ItemId),
(DENSE_RANK() OVER(ORDER BY I.ItemId ASC)) AS RowNumber,
(I.TCode), E.Name AS Source,
I.GoldenRecordNumber AS GoldenRecordNo, I.ItemCode AS MMRefNo,
I.ShortDescription AS ShortText, I.LongDescription AS POText,
Suppliers.Description AS Manufacturer, Suppliers.Name AS ManufacturerCode,
Suppliers.Abbreviation AS ManufacturerAbbr,
ItemSuppliers.ReferenceNo AS PartNumber, ItemSuppliers.ReferenceNo AS ModelNumber,
UOM.Name AS ItemUOM, MG.Name AS PSGC,
NM.Noun AS ClassName, NM.LongAbbrevation AS ClassDescription
INTO
#Results
FROM
Items I
LEFT JOIN
ItemSuppliers ON I.ItemId = ItemSuppliers.ItemsId
LEFT JOIN
Suppliers ON ItemSuppliers.ManufacturerId = Suppliers.SupplierId
LEFT JOIN
UnitOfMeasurement UOM ON UOM.UOMId = I.UOMId
LEFT JOIN
MaterialGroup MG ON MG.MaterialGroupId = I.MaterialGroupId
LEFT JOIN
NounModifiers NM ON NM.NounModifierId = I.NounModifierId
LEFT JOIN
AutoClass AC ON AC.ClassName = NM.Noun
LEFT JOIN
ERP E ON E.ERPId = I.ERPName
LEFT JOIN
NounModifierAttributes NMA ON NMA.NounModifierId =
NM.NounModifierId
LEFT JOIN
Attributes A ON A.AttributeId = NMA.AttributeId
LEFT JOIN
ItemAttributes IA ON IA.ItemId = I.ItemId
WHERE
(I.ItemCode LIKE '%'+'2001010088'+'%' )
SELECT 'Int' = COUNT(distinct(ItemId))
FROM #Results
WHERE (TCode IS NOT NULL OR MMRefNo IS NOT NULL)
SELECT DISTINCT(ItemId),
TCode, Source, GoldenRecordNo, MMRefNo, ShortText, POText,
Manufacturer, ManufacturerCode, ManufacturerAbbr, PartNumber, ModelNumber,
ItemUOM, PSGC, ClassName, ClassDescription
FROM
#Results
WHERE
(TCode IS NOT NULL OR MMRefNo IS NOT NULL)
AND RowNumber BETWEEN (1-1)*100 + 1 AND (((1-1) * 100 + 1) + 100) - 1
DROP TABLE #Results

Answer 1

if you are convinced the rows which are selected can be grouped together then it should work fine.
1. but if rows are having different data then distinct will not help.
2. use ltrim,rtrim to remove leading and trailing spaces.
example: distinct(ltrim(rtrim(ItemId)))
this will help if it due to spaces or for junk values

Answer 2

The behavior of DISTINCT works as expected. For instance, you could use GROUP BY clause to group them by ItemId, TCode to get top most records
SELECT
ItemId, TCode,
MAX(PartNumber) PartNumber, MAX(ModelNumber) ModelNumber,
MAX(ItemUOM), ...
FROM #Results
GROUP BY ItemId, TCode
In case any failure in GROUP BY clause use ranking function to assign the rank and get the record based on rank value.