What do you do for PCs that have similar non-combat skills/talents?

For instance, 2 of them have a lot to do with slicing computers. Can the other slice after the first fails, or does he get a setback, or can he not attempt it?

Any suggestions on also dealing with PCs with similar qualities like that? To keep both involved.

I tend to allow a single skill attempt in unstructured time. The other player may choose to assist and grant a boost die or two as per the normal assistance rules. If a decent modicum of time or situation alters appropriately then I will allow another attempt.

In structured time I usually allow multiple attempts by whoever wishes to attempt the action, but I often apply penalties based on rushing, improper tools, and anything else I can think of.

When two characters have overlapping talents and skills it can be tough to give each of them enough of the spotlight. It usually helps if they have different aspects of the "skill role" that they play to, but quite often that may not be enough. In that case you need to try to have multiple activities per encounter that could or should be attempted simultaneously. In the case of mechanics, one may need to slice the door while the other keeps the finnicky atmosphere system up and running. Things like that.

Social characters can get a little bit more difficult unless you split the group. In their case you may want to follow the guidelines in FH and make social combat a thing. It doesn't go into enough detail for my tastes, but it may help you determine your own system. Take a peek at FATE for some more really good ideas on how to have a social combat in structured time. It doesn't all have to be strain.

I use group checks. It takes two slicers to get through a door, one working the lock and one working the security system. In addition you might need a mechanic disabling hydraulics on the door as well, all simultaneously. Have similar rules for other skill groups in dire circumstances. Promotes group cooperation and encourages cross specialization, like a real elite team would actually operate.

1) Engage them in their other skill sets, if they have any. Presumably one has a higher Intellect, and thus might make a better mechanic: maybe he is needed to repair a conduit so that the other slicer can actually complete a connection. Maybe one is a better shot with a blaster, or one is more cunning, or one is stronger. Put challenges in front of the pair that would overwhelm either one alone, but that they can defeat together.

2) Going on that, you can have them actively trying to "attack" a computer system to gain entrance, and it's guarded by an anti-slicer droid brain, or an enemy slicer (either physically there or a program he wrote & left running). Have it take place in structured time, and they need to cause enough "damage" to the opposing slicer so that they can gain entry to the system before an alarm goes off, or before enemy troops arrive, or before the building explodes, or the cave collapses, or the starship jumps to hyperspace to collide with a nearby star.

Keep things frantic and fast-paced. Make PCs choose between what they could do vs. what they must do, to survive. Unless these PCs are clones of each other, they're gonna have different skill sets...so when the stakes are high, they can either work together (turn-based) or work separately (narrative, non-structured), always towards to the same goal.

Either that or set up a rivalry between them..."who can be the best slicer." Then have the loser get all jealous and bitter and become an NPC (or not!) and go off to start his own criminal organization that comes back and bites the PCs in their collective backsides. That's fun, too.

Splitting the party, particularly if it is a regular thing, is also a good way to make use of both people's skills. In our group, splitting the party is such a common occurrence (Team's modus operandi, really) that we all but require every skill to have two practitioners. (Though usually it's different primaries followed by an overlapping secondary or two) Splitting the party is a good way to create an effective simultaneous need of the same skill by ensuring that "the slicer" can't be in both locations, and therefore "Slicer 1" handles problems A, B & C while "Slicer 2" handles problems D, E & F.

Loads of good suggestions here.

I'll add in add in competing demands on their time, to try and persuade only one to be able to do it, a combat is one way, best rotate enemy types from encounter to encounter to try and fit two mechanics/slicer/etc combat skills in a way that favours one over the other. Of course just making sure theres more to go around.

Best also not to use the same thing every time, group tasks, more than one task, distracting NPC, combat, hell even throwing in a few where none of this is used.

Then theres modifying the checks involved. Allow advantage to allow more attempts, threat to ramp up setback, despair can easily fry the terminal and bring in the heavies. Hell Destiny point your way to upgrade checks etc.

Then theres not making success/failure of die directly correlate with the task success/failure, frame the die roll as something like doing it undetected for a slice or similar, this can quite nicely prevent sequential tests. Hell after a few tests like this you can start slipping them the o bit of flat out wrong info for a failure with threat/despair (remember you can secretly record threat and despair results for things that PCs trigger that they can't see/hear/sense).