The odds of getting a 4 of a kind given 7 cards (2 in your hand and 5 on the board) are (13 * (48 choose 3)) / (52 choose 7) or 0.00168067227. The probability of getting that specific 4 of a kind again are now (48 choose 3) / (52 choose 7) or 0.000129282482.
The probability of both events occurring is 0.00168067227* 0.000129282482, which is 0.000000217281482.
Note that this leaves open the possibility that other people at the table would also still have the four of a kind (as in, it includes those situations where there is a four of a kind on the board.) Presumably, you'd want to exclude those.
For this, we have to multiply the probability of getting 3 of a kind on the board while having an unpaired hand with the probability of getting 2 of a kind on the board while having a paired hand.
So the probability of an exclusive four of a kind is:
(48 choose 3)/(50 choose 5) * (78/1326) + (47 choose 2)/(50 choose 5) * (1248/1326) = 0.000960384154
The probability of getting the same exact four of a kind is then:
(48 choose 3)/(50 choose 5) * (6/1326) + (47 choose 2)/(50 choose 5) * (208/1326) = 0.000116969865.
So the final probability is 0.000116969865 * 0.000960384154 = 0.000000112336005.
So basically: 8,901,864 : 1 odds of you getting the same four of a kind assuming you are the only one with the four of a kind each time. Otherwise, 4,602,324 : 1 odds of you getting the same four of a kind twice.