Whenever, contrary to the provisions of this chapter, a municipality has conducted one or more sales for unpaid taxes and assessments, and the land sold at said sales has previously been sold to the municipality by tax sale, and has failed to include the amount of prior liens and tax sales purchased by such municipality, the first sale of any such land to the municipality, as held under the provisions of this chapter, shall be considered as the legal and binding sale of said land, and all subsequent sales thereof to the municipality where the former tax liens were purchased by the municipality are hereby declared to be void and without effect, and the lien of the subsequent taxes and assessments shall remain as a lien on said lands as though no sale had been made, and shall continue as liens until the amount thereof, with interest, as provided in this chapter has been paid.