Something wrong/ funny with this, but cannot figure it out

[xzaqus]

I have times in my sheet and for some reason one of the entries of 11AM is apparently not same as other 11AM. Attached is the sheet that shows that there is a difference and I cannot seem to figure out why.
Any suggestions for avoiding this as such issues alter the results.
Here is the file for reference.

 

[AlphaFrog]

Select column A and format the cells as Number with 16 decimals. You'll see that one time value is slightly different.

 

[xzaqus]

That's correct and so the difference in column C. But, it was entered as 11am just like other values. Why is this different?

Select column A and format the cells as Number with 16 decimals. You'll see that one time value is slightly different.