How can I prevent duplicate log messages using Log4j and SLF4J in a Java application?

I have partially solved this problem yesterday. There aren't duplicates anymore in the loggings, but I have noticed that the loggings stop coming in after a short while. I assume it has something to do with the strictness in my filter in the DuplicateMessageFilter class.This is the appender what I added yesterday and the regarding class as well:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration>

<List of other appenders>

<appender name="consoleAppender" class="org.apache.log4j.ConsoleAppender">
    <param name="Target" value="System.out"/>
    <layout class="org.apache.log4j.EnhancedPatternLayout">
        <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss}|%p|%m%n" />
    </layout>
    <filter class="com.someanonymouspackage.DuplicateMessageFilter">
    </filter>
</appender>

<List of logger elements>

<root>
    <priority value="debug" />
        <appender-ref ref="consoleAppender" />
    </root>
</log4j:configuration>

public class DuplicateMessageFilter extends Filter {
    private static final Set<String> messageCache = new HashSet<>();
    private static final long CACHE_TIMEOUT = 5000;
    private long lastLogTime = 0;

    @Override
    public int decide(LoggingEvent event) {
        String message = event.getRenderedMessage();
        long currentTime = System.currentTimeMillis();

        if ((currentTime - lastLogTime) > CACHE_TIMEOUT) {
            messageCache.clear();
        }

        lastLogTime = currentTime;

        if (messageCache.contains(message)) {
            return Filter.DENY;
        } else {
            messageCache.add(message);
            return Filter.NEUTRAL;
        }
    }
}

See the bellow points in order to fix the issue.

1. Log through SLF4J only.
2. Check for multiple appenders targeting the same output.
3. Ensure only one logging implementation is present on the classpath.
4. Set additivity="false" to avoid message propagation.
5. Avoid duplicate logging statements in your code.
6. Make sure there is a single SLF4J binding.

By following these steps, you should be able to prevent duplicate log messages in your Java application.