Emihamn and Emibas are both transcribed records made from the original handwritten records, but they are made from different sources.
Emibas was made from information in the parish records telling that the person was leaving for North America or some other foreign destination. The dates were written as numbers so if the numbers were scribbled, the transcriber may have guessed incorrectly about the date written so long ago.
Emihamn was made from registrations with Swedish port police before leaving the country. The travel agents (ticket agents) wrote down who purchased the tickets and also had to include information about those people. Their lists had to be submitted to the port police. Those records are also handwritten and there is always a chance of error reading those documents and trying to figure out the dates and so forth.
It is really important to look at those handwritten records and decide for yourself what they say. The parish records are on the fee-based Genline site. The other records can be seen on microfilm ordered from a Family History Center. (The parish records can also be ordered from a Family History Center but since they are online, it is more convenient -- and probably less expensive in the long run -- to subscribe to Genline. There is a fee of about $5.50 per microfilm for a month's use at a Family History Center and there is a long delay between ordering and seeing the film. With Genline, you can immediately see the same records after you subscribe.)
Obviously, the date they registered to leave the parish is going to be earlier than the date they registered at the port to leave the country. They had to travel to the port city. Since Emibas and Emihamn are made from two separate sources, the dates of registration will be different for both.
To research these people in the U.S., try the Swenson Swedish Immigration Research Center. They have a website but their extensive collection of records is NOT online.