Felix the Cat cartoons are nearly always in two parts because this allowed Pathé to chop them up conveniently into two for release on 9.5mm for home viewing. Sometimes only the 9.5m versions seems to have survived and, as they were invariably re-titled, one has two separate films instead of one and sometimes only one of the two.
Felix in the Bone Age exists for instance as Felix at the Museum (Felix gets thrown out of the museum after trying to steal a dinosaur bone and lands on his head) and Felix in the Stone Age (where he awakes to find himself in the Stone Age) but a more or less complete version does also exist although I suspect the final pay-off (connecting the two parts and indicating it was all a dream) is still missing.
In the case of Fifty-Fifty or Felix Fifty-Fifty, there is no full version that I know of. The two halves on 9.5m were re-titled Félix le chat chausse mieux/Felix the Puss for boots and Félix a des déceptions d'estomac. In the first part Felix meets an old friend who is in agonies because his shoes are worn out. By dint of a bit of caterwauling, Felix gets shoes thrown at him and is able to help his friend out. Later however when the two are hungry, Felix manages to find them both food, but the friend eats all of it without troubling to share with the unfortunate Felix.
The second part I have not seen anywhere but the first part can be found in both an English and German version (Ja aber der Kater Felix hat doch die besten Schuhe). The feel-good first half evidently appealed more than the rather depressing second half. Again, there may have originally been a more mitigating pay-off that was cut when the film was divided.