Help with validating data

[Anonymous]

Hey guys,

I need your help with a couple of calculated column or measures.

Below my sample data:

Source   Key Validation
a            3      Needs Checking
a            1      Needs Checking
a            1      Needs Checking
a            1      Needs Checking
a            1      Needs Checking
b            2      Good
b            2      Good
b            2      Good

What I need is for the "Validation" column to tell me if the source values contain more than 1 "Key" for each "Source". In the above sample, Source "b" is fine because it only has the Key "2", while Source "a" is not ok because it contains Key "1" four times and also Key "3".

Secondly, I also need to know if the same Key value is present in more than one Source. Below, another sample. In the sample, Key "3" is present in Source "a" and "C", which isn't ok.

Source   Key  Validation             Validation2
a            3      Needs Checking    Needs Checking
a            1      Needs Checking    Needs Checking
a            1      Needs Checking    Needs Checking
a            1      Needs Checking    Needs Checking
a            1      Needs Checking    Needs Checking
b            2      Good                      Good
b            2      Good                      Good
b            2      Good                      Good

c             3     Good                    Needs Checking

[Greg_Deckler]

For the first one:

Validation Column =
  IF(
    COUNTROWS(
      SUMMARIZE(
        FILTER('Table',[Source] = EARLIER([Source]),
        [Key]
      )
    ) > 1,
    "Needs Checking",
    "Good"
  )

For the second:

Validation Column 2 =
  IF(
    COUNTROWS(
      SUMMARIZE(
        FILTER('Table',[Key] = EARLIER([Key]),
        [Source]
      )
    ) > 1,
    "Needs Checking",
    "Good"
  )

[Anonymous]

Thank you Greg, your solutions work. 

For future people who need this, there is a ")" missing after each EARLIER([Key]),