Check your field types: the most likely reason is that
changes
is not an NVARCHAR column, so your two dates bolted together are being converted to whatever datatype that is.
A quick check locally:
SELECT CAST(CAST(GETDATE() AS DATETIME2) AS NVARCHAR(30)) + '-->' + CAST(CAST(GETDATE() AS DATETIME2) AS NVARCHAR(30))
Shows a perfectly valid string:
2015-03-10 11:42:52.2230000-->2015-03-10 11:42:52.2230000
So it has to be part of the INSERT operation.