And so you will inherit a double portion in your land, and everlasting joy will be yours. (Isaiah 61:7 NIVUK)
A double portion means to me that God is giving me a double portion of Him. Not that technically He can be doubled but He ministers to me in a way that I can be closer to Him. He gave Hannah a double portion through her husband so that she would know he loved her. She had a consecrated (devoted to God) Samuel soon after. So we get a double portion because He’s close to us and because He wants us close to Him
There’s a song that says a young man loved a young lady and built her a castle. He offered but she refused. He loved her and offered a double portion of himself. But what he decided was that even though she didn’t return his love “she didn’t have to love him for him to love her all he can.” That’s God. He loves us no matter what.