In the case where a person who falls under Article 19-3, paragraph (1) of the New Inheritance Tax Act is a person who, with regard to inheritance tax on property acquired by inheritance or bequest on or before December 31, 1987 by that person or by a person under a duty of support prescribed in paragraph (2) of that Article, has been subject to the application of Article 19-3, paragraph (1) or (2) of the Inheritance Tax Act prior to amendment by the provisions of Article 3, the Inheritance Tax Act prior to amendment by the Act Partially Amending the Inheritance Tax Act (Act No. 15 of 1975), or the Inheritance Tax Act prior to amendment by the Act Partially Amending the Inheritance Tax Act (Act No. 6 of 1973) (hereinafter collectively referred to as the "Former Act" in this Article and the following Article), the amount that that person or that person under a duty of support can have deducted under the provisions of Article 19-3, paragraph (1) or (2) of the New Inheritance Tax Act is, notwithstanding the provisions of paragraph (3) of that Article, the amount up to the amount obtained by deducting the total of the amounts already deducted under the provisions of Article 19-3, paragraph (1) or (2) of the Former Act or Article 19-3, paragraph (1) or (2) of the New Inheritance Tax Act from the amount that could have been deducted if the provisions of Article 19-3, paragraph (1) of the New Inheritance Tax Act were applied to that inheritance tax (where deduction under the provisions of Article 19-3, paragraph (1) or (2) of the Former Act was received two or more times, the amount that could have been deducted if the provisions of Article 19-3, paragraph (1) of the New Inheritance Tax Act were applied at the time of first acquiring property by inheritance or bequest).