If someone has got several blueprints of the same type only the highest counts towards the score.
Calculation of the Blueprint ScoreEdit
The score is the revenue multiplier multiplied by 10.
Boots have a revenue of $13,000.
Boots I (Upgrade Level 21) have a revenue of $39,000. Thus the revenue is tripled.
3 x 10 = 30
Calculation of the Set ScoreEdit
Sum the scores and then multiply by the log10 of the lowest score. If the set is incomplete ("all blueprints" will always be incomplete) then the lowest score is treated as 10 (the log10 of which is 1).
Knife Set with Sickle (score: 64) and Magnificent Dagger (score: 50).
(64 + 50) * log10(50) = 114 * 1.67
114 * 1.67 = 194
Final Knife Set Score: 194.
So it can be quite advantageous to level up all blueprints in a set, as the multiplier can factor in quite heavily (raising everything from 1 to 11 increases the total set score by ~30%, regardless of how big the set is, as it raises the lowest score from 10 (multiplier of 1) to 20 (multiplier of 1.3)).