Yerushalmi Yevamot 13:11 ירושלמי יבמות י״ג:י״א

MISHNAH: Somebody was married to two underage orphan girls and died. If the levir had intercourse with the first one¹¹²She then is married to him in levirate by biblical standards. and then had intercourse with the second, or his brother had intercourse with the second¹¹³These acts are sinful, but since the first levirate was legitimate, the sins of others cannot influence the status of the blameless wife., the first one was not disabled. The same holds for two deaf-mutes. An underage girl and a deaf-mute. If the levir had intercourse with the underage girl and then had intercourse with the deaf-mute, or his brother had intercourse with the deaf-mute, the underage girl was not disabled¹¹⁴This is also the reading in the Babli of the Babylonian Gaonim and Maimonides. But the Western tradition, represented by Rashi, RaBaD, and the printed Babli text, reads: “the underage girl was disabled”. This is explained as a rabbinic decree to assimilate this case to the next one. Since the Mishnaiot are formulated to express the non-symmetry of the situations, the Eastern reading is to be preferred.. If the levir had intercourse with the deaf-mute and then had intercourse with the underage girl, or his brother had intercourse with the underage girl, the deaf-mute was disabled¹¹⁵This Mishnah very definitely holds that the status of the deaf-mute is inferior to that of the underage girl. If the underage girl had not been an orphan, she could have been a wife by biblical standards. The marriage of the deaf-mute is a purely rabbinic institution to ensure that she should have a home and not be an object of public sexual abuse. Therefore, the almost biblical levirate of the underage girl annuls the purely rabbinic levirate of the deaf-mute, forbids the latter to the levir, and leads to the problem of the permanently forbidden deaf-mute discussed in the preceding Halakhot. As a consequence, both widows are forbidden to the levirs.
A totally different tradition is preserved in Tosephta 13:7. There, it is held that if any levirate is not 100% biblical, any doubling forbids both widows for all levirs..

HALAKHAH: “Somebody was married.” Even if he did not have intercourse with the underage girl, the deaf-mute is disabled¹¹⁶In the presence of an underage widow, the candidacy of the deaf-mute widow for levirate is not executable. As an earlier Mishnah stated, intercourse with the deaf-mute does not free the underage girl. The candidacy of the deaf-mute could be resurrected only if the underage girl died before she was married by the levir.
It is obvious that if the case involves a biblically married woman and a deaf-mute or an underage girl, the same situation applies.. If he did not have intercourse with the underage girl and she died, he would have been permitted the deaf-mute. But now that he did have intercourse with her, even if she died he had disabled the deaf-mute.