Power of Collector to correct clerical, etc., mistakes in declaration or award.

Any clerical or arithmetical mistake in the declaration made under section 21, or in an award made under section 25, or error arising therein from accidental slips or omissions, may 1* * * *be corrected by the Collector, either of his own motion or on the application of a person interested in the declaration or award, and the declaration or award as corrected, shall be deemed to have been amended accordingly: 2[Provided that, no declaration or award shall be corrected unless an opportunity is given to the person whose interest may be affected as a result of such correction to be heard.]