If there is a direct dependency in pom Maven will use it and omit any transitive dependencies to the same artifact, eg here
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-core</artifactId>
<version>2.12.1</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.5</version>
</dependency>
camel-core has a transitive dependency slf4j-api-1.6.6 but Maven will choose slf4j-api-1.7.5