From your description above this could be a solution.
DECLARE @T TABLE (AttemptDiff TIME)
DECLARE @FirstTry DATETIME,
SET @FirstTry = GETDATE()
WAITFOR DELAY '00:00:05' --Assume user attempt for second try after 5 seconds
SET @SecondTry = GETDATE() --grab the second try
SET @DiffSeconds = DATEDIFF(SECOND, @FirstTry, @SecondTry) --get the difftime
SET @FirstTry = DATEADD(second, @DiffSeconds, @FirstTry) --Add it to the first try
INSERT INTO @T
SELECT CONVERT(VARCHAR, @FirstTry, 108) -- Insert it to table.
SELECT * FROM @T t
This solution could work fro SQL Server 2012 for other version keep the time as varchar.