Can two drives connect to a single motor?

From a technical perspective, the output of both VFD's would have to be precisely synchronized (frequency) and would both have to precisely share the load. Emotron does this with its power modules - but they are specifically designed to work in parallel to achieve a compact solution for larger HP's. A lot of development time was spent engineering this concept.

Probably because of the cost/benefits ratio. If it is less expensive to parallel two smaller less expensive vfds to accomplish the same thing that you can than say..with one larger perhaps much more expensive single vfd...why not do it, as long as it complies with the electrical code.

I don't think the cost ratio is a factor. It is typical for the cost of VFD's per HP to get lower as the HP increases, in other words, a single 100 HP VFD is typically less expensive than two 50's. Also, as I mentioned earlier, you cannot connect the output of two drives in parallel; their frequencies not only have to be precisely equal but also have to be precisely synchronized, and their load precisely shared.
Electrical code is really irrelevant if the technical aspect cannot be achieved.

In low voltage we are using that kind of approach when the application is critical and redundancy is required. The load can be controlled with reduced capacity if not all AC drives are in operation. For example with 4 drives if one fails the other three can still be used to run at 75% of nominal power. We use drive sync application where the separate standard AC drives are syncronized via fast bus. It is enough to have the drive sync application, fast bus between drives and AC chokes in the outputs. Another situation is when the motor has separate windings driven by separate drives with drive sync. in this case chokes not necessary. Another benefit is the possibility to have an optimized form factor of drive: several small ones instead of one large AC Drive in places where one large does not fit.

Depends, first paralleling inverters is common in both high hp and medium voltage applications. but the inverters must have a common controller. In other words both inverters are controlled by a single system. That isn't specifically 2 separate drives on one motor. but similar. However, to operate a single motor from 2 drives is also possible if the drives are filtered using a sinewave filter to remove the majority of the carrier frequency. Also, the fundamental frequencies must be synchronized, but that really shouldn't be difficult. Otherwise, the drives will fight each other and may have circulating currents to the extent of the frequency misalignment. And finally it is a good idea to use a interphase transformer or balancing reactor. It is possible to develop a sinewave filter to incorporate a balancing reactor as the inductor portion of the sinewave filter.

Yes, this is quite common in medium voltage drives when the motor power climds above 25MW and a single converter brifdge does not exist at these levels. Siemens has done this with several topologies including an NPC, cascaded H-bridge, and LCI all various types of drives. There are some coordination issues and in some cases that have to be addressed and additional output filtering or impedance must be added to ensure proper operation. It has been done for quite some time and is a proven application in the very high power ranges where two bridges are the only solution. Only the venerable LCI which has over 40 years of history and service can achieve the very high power ranges and even that uses multiple bridge (parallel VFDs) on the high power motors (50MW and higher). The Siemens website for medium voltage drives has some application notes for parallel medium voltage drives and I have seen several websites where standard low-voltage drives were paralleled to geta higher HP rating although the cost tradeoff should be evaluated at these low power levels.