This is an unofficial version of a Massachusetts General Law.
Section 2-509
(a) If a subsequent will that wholly revoked a previous will is thereafter revoked by a revocatory act under section 2-507(a)(2), the previous will remains revoked unless it is revived. The previous will is revived if it is evident from the circumstances of the revocation of the subsequent will or from the testator's contemporary or subsequent declarations that the testator intended the previous will to take effect as executed.
(b) If a subsequent will that partly revoked a previous will is thereafter revoked by a revocatory act under section 2-507(a)(2), a revoked part of the previous will is revived unless it is evident from the circumstances of the revocation of the subsequent will or from the testator's contemporary or subsequent declarations that the testator did not intend the revoked part to take effect as executed.
(c) If a subsequent will that revoked a previous will in whole or in part is thereafter revoked by another, later, will, the previous will remains revoked in whole or in part, unless it or its revoked part is revived. The previous will or its revoked part is revived to the extent it appears from the terms of the later will that the testator intended the previous will to take effect.