Why don't you just use CFrame?
local dummy = workspace.Dummy
local dummy2 = workspace.Dummy2
local dummyhum = dummy.HumanoidRootPart
dummyhum.CFrame = dummy2.HumanoidRootPart.CFrame
Always remember, when moving a player or a rig, move the HumanoidRootPart, never the Humanoid itself. Humanoid is only for player / rig Properties.
Also remember to simplify your techniques. Roblox Characters already have attachments inside of them, so you can just use CFrame to move them about. CFrame(s) work better in situations requiring characters.
Here's an alternate script that explains what I commented, below.
local dummy = workspace.Dummy
local dummy2 = workspace.Dummy2
local dummyhum = dummy.PrimaryPart
dummyhum.CFrame = dummy2.PrimaryPart.CFrame
2 comments
Try using dummy.PrimaryPart instead of dummy.Humanoid
Make sure to unanchor all of the BaseParts inside the dummy.