[NAME]  The first question is which generation of E-Port dock you have, since that will affect available video bandwidth.  The "PRO2X" moniker was used across both generations and I think even between the regular E-Port dock and the E-Port Plus dock, so it isn't all that helpful.  The way to identify a second gen dock is by the color of the rear USB ports, since the second gen also added USB 3.x ports on the rear.  If those ports are blue, they are USB 3.x and you have a second gen dock.  If they are black, they are USB 2.0 and you have a first gen dock.  The USB ports on the left of the dock are always black and always USB 2.0.First gen docks only support DP 1.1a signals from the source system, which isn't even enough to run your 3440x1440 100 Hz display on its own.  But second gen docks support DP 1.2, and the E7440 can send a single DP 1.2/HBR2 interface worth of bandwidth to the dock, which can be subdivided between two displays thanks to DisplayPort MST. (Other systems with discrete GPUs can send two full interfaces of bandwidth to the dock.)  A single HBR2 interface is enough for setups like dual 2560x1440 60 Hz or single 4K 60 Hz.  Having done the math on the bandwidth required for 3440x1440 100 Hz + 1080p 60 Hz, that would appear to require 15.7 Gbps of effective (post-overhead) bandwidth.  A full DP 1.2/HBR2 interface supports 17.2 Gbps of effective bandwidth.  And I do know that the Intel GPU in your system can run at least 120 Hz in general, assuming sufficient bandwidth.  So the numbers suggest that you'll be ok, assuming you have a second gen dock.  But I'll add the obligatory caveat here that not everything that SHOULD work in tech always DOES work, and I don't have a way to test this specific combination myself.
Hi.I'm looking into buying a 34'' monitor with 3440 x 1440 resolution at 100hz.I want to combine this with a second monitor witch supports 1920×1080 at 60hz with my Latitude E7440 and Pro2x docking station.What is the maximum resolution  and hz I can obtain with both monitors connected simultaneously with this combination? 
3440×1440 + 1920×1080 with Latitude E7440 + Pro2x docking station