A double-pipelink does not, at the time of writing, exist within E2. However, it would be nice if it did. It would enable you to simultaneously provide pipelink commentary (see Pipe links and three-dimensionality), and link to further (different) sources of information. Let me elaborate.
[Julius Caesar|Friends, Romans, countrymen|Friends, noders, Everythingians]!
What you see in the node will be the phrase "Friends, noders, Everythingians" highlighted in blue and underlined, indicating the presence of a hardlink.
What you see when you hold your mouse over the hardlink is a small tooltip, containing the phrase "Friends, Romans, countrymen". This tells you it's a pipelink.
What you get when you click the link is something else again. Instead of searching for "Friends, Romans, countrymen", it searches for the double-pipelinked phrase, which is "Julius Caesar".
[commonly misheard lyrics|kiss the sky|kiss this guy]
[nodes with one letter of difference|I'd like to buy the world a coke|I'd like to buy the world coke]
[Wayne's World|Schwing!|Tia Carrera]
This is entirely possible using ordinary HTML, but not currently achievable within E2 writeups. Then there's the other problem. What if you want to add commentary to a hardlink but don't want to change its destination node? In the absence of a second type of pipelink (may I suggest "¦"?), you can simply do this:
Now, I see that it may be a little surprising sometimes to click a double-pipelink expecting one thing and getting another. You could compensate for this by perhaps displaying the true destination in the status bar, though personally I'd probably find that even more annoying. It's not a perfect solution. It's not really that much of a problem in the first place. Ah well. File under "never gonna happen".