It is narrated from Sa'id bin al-Musayyib and Sulayman bin Yasar (may Allah have mercy on them) that Tulayhah was married to Rushayd al-Thaqafi, and he gave her an irrevocable divorce (talaq battah). She married during her 'iddah, so Umar bin al-Khattab (may Allah be pleased with him) struck her and struck her (new) husband several times with a whip, and separated the two of them. Then Umar bin al-Khattab (may Allah be pleased with him) said: "Any woman who marries during her 'iddah: if the husband who married her has not consummated the marriage with her, they are to be separated, then she completes the remainder of her 'iddah from her first husband, and he (the second man) is (free to propose to her) like any other suitor. If he has consummated the marriage with her, they are to be separated, then she completes the remainder of her 'iddah from her first husband, then she observes the 'iddah from the second, and then he may never marry her."
Sa'id (may Allah have mercy on him) said: "She is entitled to her dowry, because of what he made lawful for himself of her."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15539
Sayyiduna Ali (may Allah be pleased with him) ruled, concerning a woman who married during her 'iddah, that the two of them are to be separated, and she is entitled to the dowry because of what was made lawful of her private parts; and she is to complete her 'iddah, then observe the other 'iddah as well.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15540
Ali (may Allah be pleased with him) said concerning a woman who married during her 'iddah: She completes the remainder of the first (husband's) 'iddah, then observes a new 'iddah from the second husband.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15541