Transact-SQL - Select query returns far more results when put in stored procedure (urgent please)

I have a select query like this

SELECT master_feed_product.id as MasterFeedProductId
,ISNULL(MasterTaxonomy.Id , -1) AS MasterCategoryId
,ISNULL(MasterTaxonomy.CategoryName, 'Unmapped') AS MasterCategory
,[mf_product_title] AS ProductTitle
,[mf_product_sku] AS ProductSku
,SUM(partner_click.p_click_cost) AS TotalCost
,SUM(ISNULL(product_checkout.total, 0)) AS SalesRevenue
,COUNT(product_checkout.itemcount) AS OrderCount
,[TopProduct] AS TopProduct
,[price_col_value] AS Price

,master_feed_product.[created]AS CreatedDate



FROM [onefeed].[dbo].[master_feed_product]

LEFT OUTER JOIN MasterTaxonomy
ON MasterTaxonomy.Id = master_feed_product.TaxonomyId

INNER JOIN feeds
ON feeds.id = master_feed_product.feed_id

INNER JOIN brands
ON brands.id = feeds.brand_id
AND
(@localMerchantId IS NULL OR brands.merchant_id = @localMerchantId) AND
(@localBrandId IS NULL OR brands.id = @localBrandId)
full outer join partner_click
On master_feed_product.id = partner_click.product_id



full outer join product_checkout
On partner_click.merchant_id = product_checkout.merchant_id AND
partner_click.product_id = product_checkout.product_id AND
partner_click.click_id = product_checkout.click_id

where

(@localActive IS NULL OR master_feed_product.Active = @localActive)

and
(ISNULL(@localMasterCategory, '') = '' OR MasterTaxonomy.CategoryName like @localMasterCategory)

And
(@localDateFrom IS NULL OR master_feed_product.created >= @localDateFrom) AND
(@localDateTo IS NULL OR master_feed_product.created <= @localDateTo) --AND
--partner_click.is_bot = 0
AND
ISNULL(product_checkout.duplicate, 0) = 0


GROUP BY master_feed_product.id,
MasterTaxonomy.Id,
MasterTaxonomy.CategoryName,
master_feed_product.mf_product_title,
master_feed_product.mf_product_sku,
master_feed_product.TopProduct,
master_feed_product.price_col_value,
master_feed_product.created



ORDER BY master_feed_product.id



But when i put this is a stored procedure, I get far more results than it is ...

How can i modify my sp to have corect values

This is the longest and most complicated SELECT query I've seen. Think you might have too many groups in the GROUP BY clause. Suggest you start with a simpler query and then build up. Try just one aggregate function and one group then if results make sense add another aggregate function. At some point the combination will bring a failure, as you have now. You might find it necessary to do multiple queries. What database app are you using?