I've spent some time trying to get some dynamic elements onto a page that is rendered as a pdf.  I've isolate what I believe to be a bug and would like for someone to verify.  In order to combat the various problems around losing state of member variables in page flows that contain the same controller, I've packed the url that I redirect to with query string parameters that will then be used by the target page to fill content.  Like so:

String url = '/apex/PrintMultipleSOs?id=' +
        ApexPages.currentPage().getParameters().get('id');
        Integer counter = 0;
        signaturePageItems = myServiceMap.values();
        for (Service_Order__c eachSO: signaturePageItems){
            if (counter == 0){
                //i'm hacking this because having trouble with the map and the signature page items array
                url = '/apex/PrintMultipleSOs?id=' + eachSO.id;   
            }
            else {
                url += '&so'+counter+'='+eachSO.Id;
            }
            counter++;
        }
        PageReference sigPage = new PageReference(url);
        sigPage.setRedirect(true);
        return sigPage;

So if I have 3 SOs, I'll end up with a query string that is {url}?id={firstRowID}&so1={secondRowID}&so2={thirdRowID}.

So now in my target page, I'll need to query for these so I want to just iterate over the map of values from 

ApexPages.currentPage().getParameters().  (side note that when working in dev mode there is a query string parameter that was causing my iteration to fail until I removed it from my user profile)

//this will never work for a user that is in dev mode b/c there is an additional qs parameter for the dev mode
              Map<String, String> soList = ApexPages.currentPage().getParameters();
              //todo: pull the query into a list return, rather than adding to temp array and potentially hitting soql limit
              for (String eachSOID:soList.values()){
                  tempService = [select Id,Name,Order_Stage__c, Product__c, Term__c, Product_Category__c,
                Hub_Circuit_ID__c, Flex_Facility_ID__c, Ring_Name__c, Bandwidth__c,Customer_Circuit_Id__c,
                Customer_PO__c, Auto_Switching__c,Card_Protection_Required__c,Core_Network_Protection_Required__c,
                Colocation_Type__c, Cabinet_Rack_Provided_By__c, Primary_Power__c, Redundant_Power__c,
                Address_A__c, Suite_Room_A__c, City_A__c, State_A2__c, Zip_A__c, Address_Z__c, Suite_Room_Z__c, City_Z__c, State_Z__c, Zip_Z__c,
                Account__c from Service_Order__c where id = :eachSOID];
                myServiceMap.put(tempService.id, tempService);
               
              }

So this works fine when the target page is not a pdf.  I'm guessing there's another hidden querystring param (like the dev mode stuff)  However, brute force does appear to work on the target page.  Like so:

String so1 = ApexPages.currentPage().getParameters().get('so1');
              tempService = [select Id,Name,Order_Stage__c, Product__c, Term__c, Product_Category__c,
                Hub_Circuit_ID__c, Flex_Facility_ID__c, Ring_Name__c, Bandwidth__c,Customer_Circuit_Id__c,
                Customer_PO__c, Auto_Switching__c,Card_Protection_Required__c,Core_Network_Protection_Required__c,
                Colocation_Type__c, Cabinet_Rack_Provided_By__c, Primary_Power__c, Redundant_Power__c,
                Address_A__c, Suite_Room_A__c, City_A__c, State_A2__c, Zip_A__c, Address_Z__c, Suite_Room_Z__c, City_Z__c, State_Z__c, Zip_Z__c,
                Account__c from Service_Order__c where id = :so1];
                myServiceMap.put(tempService.id, tempService);
               
                String so2 = ApexPages.currentPage().getParameters().get('so2');
                tempService = [select Id,Name,Order_Stage__c, Product__c, Term__c, Product_Category__c,
                Hub_Circuit_ID__c, Flex_Facility_ID__c, Ring_Name__c, Bandwidth__c,Customer_Circuit_Id__c,
                Customer_PO__c, Auto_Switching__c,Card_Protection_Required__c,Core_Network_Protection_Required__c,
                Colocation_Type__c, Cabinet_Rack_Provided_By__c, Primary_Power__c, Redundant_Power__c,
                Address_A__c, Suite_Room_A__c, City_A__c, State_A2__c, Zip_A__c, Address_Z__c, Suite_Room_Z__c, City_Z__c, State_Z__c, Zip_Z__c,
                Account__c from Service_Order__c where id = :so2];
                myServiceMap.put(tempService.id, tempService);

Why is this misbehaving?