It is NOT safe to obtain the grounding from another outlet.
The grounding wire must follow along side the hot and neutral wires of the same circuit for the entire path back to the panel. The reason for this is to minimize the inductance in the event of a short circuit to any grounded metal, either in work boxes, or in the powered equipment itself (such as the multi-outlet box). Surge protection will be much less effective in cases where the surge is a differential between hot/neutral and ground (which actually is a common type of surge) due to this same inductance.
Inductance is minimized when the wires with the current going in both directions are close together. Their magnetic fields overlap and mostly cancel each other out (there will be a field inside the cable between the wires). When the wires are far apart, their magnetic fields will extend a greater distance and there will be more inductance. Also, metal located inside the "loop" between the wires can be affected by the magnetics (sometimes in a hazardous way).
To correctly upgrade a 2-wire circuit to 2-wire-plus-ground circuit, the cable must be replaced with one that has integrated ground. In some rare cases, the proper cable may have been run, already, but an ungrounded outlet was used.
Simply running a single wire along side the old cable is also NOT safe. The wires of a circuit, when conducting current, will try to physically move apart from each other due to the orientation of the magnetic field. Physically binding the new single wire to the cable with cable ties not further than 6 inches apart for the entire length could avoid that issue (but is still not code compliant). If you are doing that much work, just replace the cable with the proper type. FYI, this was one of the hazards of older knob and tube wiring. Single wires inside conduit are known to move around, but the conduit sufficiently confines the movement so all you get is some noise.
In many cases you can obtain much (but not all) of the safety of grounding with the use of a GFCI outlet. The grounding wire still cannot be used in this case. It just gives a safer 2-wire load. It is not sufficiently safe for appliances that have frequent human contact, like a computer.
First off, the first electrician is wrong in saying that the use of a crimp-type terminal in house wiring is categorically unsafe. Crimp-type terminals listed under UL 486A for use on solid wire of the given gauge are considered acceptable for use in building wiring, as per UL 486A section 1.1:
These requirements cover pressure wire connectors and soldering lugs for use
with copper conductors according to the National Electrical Code, NFPA 70.
and NEC 110.14(A):
Terminals. Connection of conductors to terminal parts shall ensure a
thoroughly good connection without damaging the conductors and shall be made
by means of pressure connectors (including set-screw type), solder lugs, or
splices to flexible leads. Connection by means of wire-binding screws or studs
and nuts that have upturned lugs or the equivalent shall be permitted for 10
AWG or smaller conductors.
Terminals for more than one conductor and terminals used to connect aluminum
shall be so identified.
However, I would be quite hesitant to call this specific application fully Code-conformant -- garden-variety listed crimp terminals are listed for use with copper wire only, and it would be unlikely that the previous homeowner had access to terminals identified for use with aluminum wiring.
EDIT based on updated info about the devices:
Since the existing devices are copper only, your options go as follows (in order of preference):
- Find an electrician in your area who is qualified on the Tyco/AMP COPALUM system for pigtailing copper to aluminum -- these have a long, successful field service history, but require a specially qualified electrician to install, and are rather expensive -- you might be able to get the seller to shell out for this, though...
- Use the AlumiConn connectors with a torque screwdriver for pigtailing. This is something that most electricians can do, or you can DIY if you know your way around electricity and have a torque screwdriver -- the AlumiConn must be torqued to spec to meet its UL listing.
- Replace all the devices with modern CO/ALR types. This is a last resort as CO/ALR device performance has been historically variable, unfortunately.
Best Answer
The manufacturer of the receptacle should make this detail clear in their documentation. It might even be printed on the case of the receptacle, though perhaps in very abbreviated / "hieroglyphic" form.
That said...
My understanding is that aluminum wiring must be used ONLY with approved mechanical connectors specifically designed for aluminum, and of course must be installed correctly. So I do not see, offhand, why a separate copper connection on the same device would be a problem.
[Note - I am not an electrician. Aluminum wire done incorrectly is a huge fire hazard, which the OP obviously knows since s/he is obviously intending to do this right.]