Normally people rejoice at the idea of having two mutually friendly planets together in a house, especially when one of them happens to be in it’s own sign or an exalted sign, but this happiness is all but a camouflage and may not necessarily translate into all the said and benefits as mentioned in the ancient texts and there is a good reason why things manifest the way they do, and one should be really thankful for that!
As long as a single planet occupies a house- the interpretation of the effects of the planets energy can be deduced by simple observations related to the house signification, the relation of the house lord with the planet and the aspects of the planet from the said house and aspects on that planet! Well fairly simple until this point. The moment you have additional planets coming in- things change and they change in ways- that can confuse and amuse even the most experienced astrologers! To understand why these instances happen, by virtue of my limited experience I have been able to kind of understand and factor the developments in a very simple manner!
Whenever you have two or more planets in a single house and one of the planets also happens to own the sign in that house, it will then rub off it’s energies to others and all other planets will start to give results aligned to the signification of the planet that owns that sign. If the planet which has ownership of the sign also has the ownership of the house, than rest assured all other planets are basically sidelined and even if they may want to give results, they will be at the best sporadic and limited to their transits/antardasha periods. Furthermore the effects and manifestations will always be aligned to the planet that rules the house/sign in which these planets are residing.
In case you come across a combination of benefic and malefic, than based on the other factors taken into account, effects that get manifested will depend on which of the planet is more powerful and who owns the sign/house. Likewise, say if the malefic planet is powerful, it’s negative impact may get reduced but it will simply not allow the benefic planet to come to the forefront unless there is a Mahadasha of the benefic planet ruling with some other additional sources of strengths.
When other planets aspect houses that have multiple planets- due understanding has to be developed to check what the net effect translates into- you could have a case of positive reinforcements, negative reinforcements or nullification thereby explaining why things would have been exceptionally good, severely bad or rather average even though the planet consideration at an initial glance seem to be superlative!
For fast moving planets/the inner planets more impact is felt as they pass over houses having multiple planets during their transits, for slow moving planets- their Mahadasha/Antardasha will seem to be more pronounced. transits do certainly play out and signify more impact for these large outer planets as well but as they move slowly the impact is felt over a period of time and can be gauged relatively slowly.
When multiple planets occupy a house, and say none of them own the sign or the house, than the mutual strength of association/aspect with the dispositor of the house and the sign lord with each of the planets in that house and sign will have to be considered and then due weight age must be assigned to know who really hold the key to the signification and manifestation of the house under consideration.
Multiple planets in a house/ sign can also be used to study convergence or divergence and thereby make an individual a jack of all trades or a specialist with a laser sharp focused approach for the area which is signified by the house where these planets are seated- certainly this will depend on the house signification, sign lordship and the interplay among these elements as explained earlier!
Not to forget, planets which have avasthas more suitable and aligned to who they are will tend to have a habit of making their impact/presence felt through altering the flavor of things the way they are done or experienced by an individual! This will normally be visible as sporadic streaks of brilliance or sudden challenges form time to time. These are better understood by studying the avasthas and the transits more than other aspects and are more visible for the faster moving planets!
To sum it up, the stronger the planet in a house/sign among others, that planet gets to control the house signification and the results begin to manifest through that planet and take on the overtones of the sign significator and the other reinforcing or contradictory interplay of the other planet and interplanetary aspects in the given chart.
This, I believe is the simple crux of what my experience has been while unraveling the mysteries of multiple planets in a house in a sign! As it goes with astrology, the learning never stops and for all that you may know that you know, you may just end up going off balanced- as the next chart and challenges comes up to you!
Ciao for now, I will leave it here for now, so that you too can begin an approach to check, cross check and decipher what charts whisper unto you and that learning what you gain will go a long way for you to refine your intuition and understand the planetary whispers that come your way through the universe around us!