From the Administrator client's help:
Multi-Valued attributes
Most attributes within an object class are defined to support one value. Some attributes, however, can have many values. For example, a “person” object includes a “telephone number” attribute that allows you to specify many phone numbers. When this attribute is retrieved, the directory service can return zero, one, two, or any number of telephone numbers as atomic values.
This differs from typical database applications and the AR System in that a column or field only stores one value. If you want to store two phone numbers in such an application, you would add a new column or field to accommodate the additional data.
To resolve this difference between the two data models, you use a special notation when specifying the attribute name in the Field Properties window.
<attribute name>[*<separator string>]
Values associated with <attribute name> are concatenated into a single value in the AR System but separated with <separator string>. For example, to concatenate all values associated with the telephoneNumber attribute and separate each value with a comma you would enter the following as the attribute name in the Form Properties window:
telephoneNumber[*,]
For the creation of users you can follow the Inetorg sample from your Remedy Administrator client's help as well