ok ... both numbers have a different meaning. The first is the regular 5-digit PLAAF serial number which consists of the following code: ABxCx, so that 61675 means ABC = 61x7x and xx = 65.
Within that system, ABC minus 611 is the air brigade, that operates this particular aircraft and xx is the individual aircraft within that unit, so 617 - 611 = 6 means, this J-16 is from the 6th Air Brigade, which is based at Suixi and xx = 65 means, it is the 65 aircraft within this brigade, however there are sometimes not all numbers allocated.
The second number 1006 is the construction number of this particular J-16 and it has this system:
1006 is according to the BBxx system, a Batch 10 aircraft (BB = batch) and xx = the 6th J-16 within that batch.
Hope this helps.