Altar of Incense in the Holy of Holies?

Not long ago I received a curious question from a man who was struggling reading through the book of Hebrews in the New Testament. His question had to do with the temple and with the tabernacle arrangement, which was originally described in the book of Exodus. In Exodus the מִזְבַּ֥ח הַקְּטֹ֖רֶת (mizbeach haketoret) the altar of incense was stationed in the Holy Place. In Hebrews 9:4, however, it says that it was in the Holy of Holies. How can this be?

3 Behind the second curtain was a tent called the Holy of Holies. 4 In it stood the golden altar of incense and the ark of the covenant overlaid on all sides with gold, in which there were a golden urn holding the manna, and Aaron’s rod that budded, and the tablets of the covenant (NRSV – Hebrews 9:3-4).

The Holy Place and Holy of Holies were two separate rooms sectioned off by a curtain in the wilderness. According to Flavius Josephus, the Herod’s Temple had not only a curtain, but also the doors. The Holy of Holies was visited only once a year and was supposed to contain only the Ark of the Covenant with its contents. The מִזְבַּ֥ח הַקְּטֹ֖רֶת (mizbeach haketoret)  – altar of incense” was supposed to be on the other side of the separation in the Holy place and not in the Holy of Holies as Hebrews 9:3-4 describes.

26 He put the golden altar in the tent of meeting before the curtain, 27 and offered fragrant incense on it; as the Lord had commanded Moses. (NRSV – Exodus 40:26-27)