Dialog is shown twice

[MDXDave]

My code:

CustomDialog.Builder builder = new CustomDialog.Builder(mActivity,
                    mActivity.getString(R.string.restart_required), mActivity.getString(R.string.yes_restart));
            builder.negativeText(mActivity.getString(R.string.no));
            builder.darkTheme(false);
            builder.content(mActivity.getString(R.string.restart_now));
            builder.titleAlignment(BaseDialog.Alignment.LEFT);
            builder.titleColor(R.color.app_blau);
            CustomDialog customDialog = builder.build();
            customDialog.show();
            customDialog.setClickListener(new CustomDialog.ClickListener() {
                @Override
                public void onConfirmClick() {
                    [...]
                }

                @Override
                public void onCancelClick() {
                    [...]
                }
            });

The Dialog is shown twice on top of another, any fix available?