Arcana Coelestia#5252
5252. 'I have dreamed a dream' means a foretelling. This is clear from the meaning of 'a dream' as foresight and consequently a foretelling, dealt with in 3698, 5091, 5092, 5104, 5233. The fact that at this point 'a dream' means a foretelling is also evident from what follows, for in the dream the seven years of abundance of corn and the seven years of famine were foretold.
Arcana Coelestia#5104
5104. 'We have dreamed a dream' means a foretelling. This is clear from the meaning of 'a dream' as foresight and a consequent foretelling, dealt with above in 5091.