is the "adds STR Bonus to Damage" from
Larzuk's Round Shot
stackable with itself? As in cubing two of them on the same weapon? And how high is the value? Am i correct in assuming that it works like 
Larzuk's Round Shot
Mystic Orb
Right-Click to Apply
+10% Enhanced Damage
2% Chance of Crushing Blow
Weapon Physical Damage +30%
+20 to Strength
+10 Required Level
Limit per item: 2
Mystic Orb
Right-Click to Apply
+10% Enhanced Damage
2% Chance of Crushing Blow
Weapon Physical Damage +30%
+20 to Strength
+10 Required Level
Limit per item: 2
Shroud Royal
?
Shroud Royal
Full Plate Mail (4)
Defense: (336 - 390) to (676 - 786)
Required Level: 11
Required Strength: 35
Item Level: 29
Additional Strength Damage Bonus: 0.01171875%
+(1 to 2) to Vanquish
+(35 to 57)% Enhanced Defense
(3 to 5)% to All Attributes
Physical Damage Taken Reduced by (7 to 10)
(6 to 8)% Gold Find
(6 to 8)% Magic Find
Socketed (2)
Defense: (1082 - 1213) to (2067 - 2318)
Required Level: 28
Required Strength: 70
Item Level: 40
Additional Strength Damage Bonus: 0.015625%
+(5 to 6) to Vanquish
+(81 to 103)% Enhanced Defense
(9 to 11)% to All Attributes
Physical Damage Taken Reduced by (15 to 18)
(10 to 12)% Gold Find
(10 to 12)% Magic Find
Socketed (4)
Defense: (2707 - 2983) to (5055 - 5570)
Required Level: 46
Required Strength: 245
Item Level: 67
Additional Strength Damage Bonus: 0.01953125%
+(9 to 10) to Vanquish
+(126 to 149)% Enhanced Defense
(15 to 17)% to All Attributes
Physical Damage Taken Reduced by (23 to 26)
(14 to 16)% Gold Find
(14 to 16)% Magic Find
Socketed (5)
Defense: (4043 - 4401) to (7534 - 8200)
Required Level: 54
Required Strength: 490
Item Level: 85
Additional Strength Damage Bonus: 0.0234375%
+(11 to 12) to Vanquish
+(149 to 171)% Enhanced Defense
(18 to 20)% to All Attributes
Physical Damage Taken Reduced by (27 to 30)
(18 to 20)% Gold Find
(18 to 20)% Magic Find
Socketed (6)
Full Plate Mail (4)
Defense: (336 - 390) to (676 - 786)
Required Level: 11
Required Strength: 35
Item Level: 29
Additional Strength Damage Bonus: 0.01171875%
+(1 to 2) to Vanquish
+(35 to 57)% Enhanced Defense
(3 to 5)% to All Attributes
Physical Damage Taken Reduced by (7 to 10)
(6 to 8)% Gold Find
(6 to 8)% Magic Find
Socketed (2)
Defense: (1082 - 1213) to (2067 - 2318)
Required Level: 28
Required Strength: 70
Item Level: 40
Additional Strength Damage Bonus: 0.015625%
+(5 to 6) to Vanquish
+(81 to 103)% Enhanced Defense
(9 to 11)% to All Attributes
Physical Damage Taken Reduced by (15 to 18)
(10 to 12)% Gold Find
(10 to 12)% Magic Find
Socketed (4)
Defense: (2707 - 2983) to (5055 - 5570)
Required Level: 46
Required Strength: 245
Item Level: 67
Additional Strength Damage Bonus: 0.01953125%
+(9 to 10) to Vanquish
+(126 to 149)% Enhanced Defense
(15 to 17)% to All Attributes
Physical Damage Taken Reduced by (23 to 26)
(14 to 16)% Gold Find
(14 to 16)% Magic Find
Socketed (5)
Defense: (4043 - 4401) to (7534 - 8200)
Required Level: 54
Required Strength: 490
Item Level: 85
Additional Strength Damage Bonus: 0.0234375%
+(11 to 12) to Vanquish
+(149 to 171)% Enhanced Defense
(18 to 20)% to All Attributes
Physical Damage Taken Reduced by (27 to 30)
(18 to 20)% Gold Find
(18 to 20)% Magic Find
Socketed (6)
I would test it myself, but I don't have one of those orbs, let alone two.