I filed already but then received a corrected 1099. Total div remain the same but classification was adjusted & now box 5 199a div has an amount. is an amendment needed?

You may wish to amend your tax return. Box 5 - 199A dividends count as Qualified business income and you are entitled to a deduction of 20% of the amount shown in box 5. The IRS would most probably not bother you for not amending. It is up to you to decide whether the tax savings on 20% of the amount is worth doing the amendment.