You can see them here in the logs.
You have 4 methods to merge the cards:
1 "merge same names (strikt)":
Brings cards (contacts) together that have exactly the same name (case-sensitive).
2 "merge same names (normal)":
Brings cards (contacts) together that are "virtually" the same. Upper and lower case as well as special characters such as e.g. "-" "/" or "." as well as multiple spaces are ignored
3 "merge same names (tolerant)":
Builds on method 2 and also ignore the name type (first name, last name, title, etc.)
Forces the merge and takes the best possible name
To activate the merge mode, click on "select" at the bottom of any card. Then you can choose one of the 4 methods and mark all cards at once.
There are fields that can only exist once per card (e.g. photo). In all 4 methods, the best content is analyzed and adopted in this case.
Text fields such as the note fields are combined so that no note is lost.
In short, don't worry, vCardPro tries the best it can :)
To merge same contacts, select "merge similar cards" under the import-settings.
The contact name is decisive for the merging of the contacts, whereby multiple pieces of information are removed.
Contacts are merged per upload process.
Contacts of ONE vCard file that contain several contacts
several selected, individual vCard files (per contact) that were selected for upload (multiple selection)
Tip 1: First export all your "old" contacts as ONE vCard file, then all your "new" contacts as ONE vCard file.
Then you can select these 2 files by multiple selection and activate the "merge similar cards" option to merge them.
Tip 2: You can also use the advanced feature to have more control. Read this article.
The vCard standard has different versions (4.0, 3.0, 2.1). Certain control characters, such as Breaks or special characters are handled differently in these versions.
Normally, the version of the vCard file and the information on how these control characters are to be interpreted is contained in each vCard file.
Nevertheless, due to the export behavior of machner programs, inconsistencies can arise (mostly in note and URL fields).
To counteract this, you can change the escaping in the import settings.
You can see here how vCardPro deals with control characters.