Why are you concatenating the date with itself? What are you trying to do?
There's no problem concatenating dates if you use CONVERT()
DECLARE @SampleData TABLE(
SomeDate date)
INSERT INTO @SampleData
VALUES(GETDATE()),(GETDATE() - 1),(GETDATE() - 2),(GETDATE() - 3),(GETDATE() - 4)
SELECT CONVERT(char(10), SomeDate, 120) + ';' + CONVERT(char(10), SomeDate, 120)
FROM @SampleData