Yes, you can either force a minimum value, or ask for same value for all swimlanes:
@startuml
skinparam swimlaneWidth 400
|A|
:foo;
|b|
:foo2;
@enduml
@startuml
skinparam swimlaneWidth same
|A|
:foo;
|b|
:foo2 which is very long;
@enduml
Is this what you are looking for ?